Pharrell Williams is in love.

Maybe it won't last a lifetime or even a few years or, for that matter, the next five minutes. But at the moment, the man is smitten, and he'd like the world to know it. At minimum, he'd like the Latino babe in the clingy gray sweat pants to know it, since she's the one he's in love with.

"Sweat pants," he sighs, massaging a few sentimental chords on a white piano. "I see you, you're looking good in those . . . sweat pants."

Williams is making it up as he goes along and flirting with all his considerable lover-boy charm, killing time on a soundstage with the two other members of his band, N.E.R.D. The trio is in this cavernous room, along with Ms. Sweat Pants and a production crew that's at least 40 members strong, to film the performance segment of its latest video, an R&B heartthrobber called "Maybe." The plot, such as it is, centers on Pharrell and his longings for an ex-girlfriend, who has left town on a bus and might not be coming back.

With luck, "Maybe" will turn up soon and often on MTV's "Total Request Live," which just might perk up the tepid sales of N.E.R.D.'s second album, "Fly or Die." So far, the band has yet to launch a truly monster hit single, which is odd because launching monster hit singles is what Pharrell Williams does, it seems, in his sleep. As one-half of a production duo known as the Neptunes -- the other half is his high school buddy and N.E.R.D. band mate Chad Hugo -- Williams has programmed the beats and/or written songs for Nelly ("Hot in Herre"), Britney Spears ("I'm a Slave 4 U"), Jay-Z, Janet Jackson, Justin Timberlake and Usher, to name a few. Rock acts such as No Doubt, Garbage and Marilyn Manson have hired the Neptunes, too.

The output has been so constant and so successful that the hip-hop charts have rarely been Neptunes-free in the last few years. And not just in the United States. Last year, a survey found that one in five songs on English radio was the handiwork of Williams and Hugo. In February, the pair pocketed the Grammy for producers of the year, making them, officially, the smokingest beat-makers in the business. Now, Williams is seeking megaband status for N.E.R.D., a feat that would make him (and Hugo) the rarest of pop creatures: sought-after producers with a side project that sells.

That status is just about the only thing eluding the 31-year-old Williams these days. Unless you count the Latina at this video shoot -- though she might not be eluding him for long.

"Cut," shouts the director, after a long take.

"Sweat pants," Williams croons, picking up right where he left off. "I see you, you're looking good in those . . . sweat pants."

Williams is wearing a turquoise blazer with military ribbons over a T-shirt that reads "Billionaire Boys Club." When the filming breaks for lunch, he is soon chatting away with the inspiration for his improvised ditty, a woman, it turns out, he met for the first time last night. Then he's huddling with a team from Virgin Records, which is N.E.R.D.'s label, then the video director. Everyone wants Pharrell, and he's sharing.

This is unfortunate because at the moment Williams is supposed to be sitting in a nearby mobile home, listening to his 10 favorite songs and explaining what he loves about each tune. He provided The Post with a list of his best-loved tunes a few days earlier, and the plan was to play the music on a boombox and get him talking about himself and the artists and bands that shaped him.

In theory, it could be a fascinating hour. N.E.R.D. draws liberally from hip-hop, rock, jazz and soul, but those elements are jumbled in such original configurations that every attempt to tag the band feels foolish. It makes you wonder: Musically speaking, where did this guy come from?

The answer will have to wait. At 12:30, the stars of MTV's "Viva la Bam," a spinoff of "Jackass," visit Pharrell to shoot a quick promo with him in the parking lot of the soundstage. Someone hands him a trucker's baseball hat, which, for some reason, the "Viva" cast ritually stomps three times. Then, with the cameras rolling, Williams calls Snoop Dogg on his cell phone.

"Tell him we want a dog-bone-size blunt!" yells Bam Margera, one of the stars. Williams conveys the message.

The Neptunes' Orbit

In pop, every age has its sound and few producers have shaped the sound of today as much as Pharrell Williams and Chad Hugo. Their work is distinctly digital age, comprising hard, flat tones, repetitive electronic hooks and arrangements that make use of the silence between the beats. The Neptunes might well be the Phil Spectors of their era, but where Spector added, the Neptunes subtract. There's nothing extra on a song like "Slave 4 U." You get enough to make you dance and nothing more.

Williams was raised in Virginia Beach, the son of a handyman father and a mother who was a teacher. He met Hugo in seventh grade, when they played in the same improvisational jazz band; Pharrell drummed and Chad played sax. They began experimenting with samplers and beat production in high school, and while playing together in a talent show in 1992 they were discovered by a scout for Teddy Riley, a producer and singer. He gave them their first behind-the-boards gig, producing a track for Riley's R&B vocal group, Blackstreet.

More cachet came from producing "SuperThug" for the hard-core rapper Noreaga, and then the jobs and money started pouring in. By 2001, Williams and Hugo, along with a friend known only as Shay, had resurrected their high school band, N.E.R.D. (it stands for "nobody ever really dies"). Their debut, "In Search of . . ." drew raves from critics but didn't sell anything close to a typical Neptunes offering.

"Fly or Die" was supposed to be the band's breakthrough, and N.E.R.D. has been touring hard to generate buzz for the album. Williams, who is the most dynamic and outgoing of the trio, has done round after round of interviews. At the moment, though, he is sitting at a lunch table eating crab legs, and he barely has time to eat, let alone muse about his favorite songs.

"Sorry," says Pharrell's harried publicist, who has been negotiating with the video director for some spare time. "This will happen. I promise."

Before it does, the whole crew packs up and relocates about a mile away, to another neighborhood in the San Fernando Valley, to a recreation center with a couple acres of green grass near a bustling intersection. Late in the afternoon, a shot is set up on a nearby street, part of a vignette that has Pharrell, wearing a high school varsity jacket, chasing a bus that supposedly is carrying his girlfriend out of town. He has a couple of minutes before they actually need him to start chasing. So for the moment, he stands in a parking lot, signing the shirts and hats of 12-year-olds who recognize him. His publicist finally collars him, and he turns around and introduces himself like he's at a board meeting.

"Nice to meet you," he says, "and thanks for your patience."

The formality aside, Williams could pass for a college senior, though as he climbs into an SUV for an impromptu, two-person listening party, he has the affectless manner of a poker player who doesn't want to give any hints about his hand. He begins tearing the cellophane off the CDs bearing his top 10 songs.

"You got some great [stuff]," he says, in apparent awe.

Yeah. You chose them.

"Uh-huh," he says. This evidently jogs Pharrell's memory, but his first selection suggests that he didn't fully grasp the My Top Ten concept when he devised this list. It's "I Still Love You," a song that the Neptunes produced for a hip-hop girl group called 702.

You picked one of your own songs as an all-time fave?

"Yeah," he says, enraptured now by the sound of his own vocals, which turn up on the song's chorus. "I just like the emotion of it. You'll find that a lot of my picks are based on the fact that the songs are emotional and they take you on an emotional ride."

Williams switches discs, and "The Flower Called Nowhere" by London's Stereolab is now playing. He sinks into the seat and is silent for a minute.

"When I hear great music, I tune out whoever I'm talking to," he says quietly. "I can't help it. If something's crazy and I ain't never heard it before, I'm locked in. If it's greatness, I'm oblivious to everything. You could be smacking my girlfriend, I can't help it."

Williams, it's soon clear, isn't kidding. He zones when each of his most treasured tracks is playing, and it takes prodding to get him to say much of anything.

"I was in a restaurant in Norfolk when I heard this, and I almost killed everybody in there to get the CD," he says as "Flower" finishes up. The song bobs up and down with the vocals of lead singer Laetitia Sadier, whose voice crests and falls like a flute in a long and elegant solo.

"It's like some Christmas carol, and it sounds like Lucy and Charlie Brown doing figure eights on the ice," Williams says. "But it was summer when I heard the song first, so I knew it wasn't a Christmas song. I was like, what the [heck] is this?"

There's a knock on the window of the SUV.

"We're ready for you," says a man with a clipboard.

It's time for Williams's close-up. Or maybe it's a long shot, because for the next hour he chases a bus down a street over and over again, feigning distress, pausing a moment, then taking a right turn and sprinting up the rec center's lawn. He threads through a handful of extras, who do their best to look as if they're not in a video.

Before he trots off for this new round of filming, an agreement is struck. The interview will recommence at 10 p.m. at the Four Seasons Hotel, where Pharrell has a suite for a few days, registered under the name Luke Skywalker.

Williams spends the rest of the afternoon and much of the evening finishing the "Maybe" shoot. A crowd of Latino kids huddles around him when he has any down time. Once everyone has an autograph, Williams launches into a long monologue with a prematurely tough-looking 8-year-old boy in a black T-shirt. Evangelically against drugs -- Pharrell says he doesn't use them, nor does he drink or smoke -- he lectures the boy for 15 minutes, until it's time for another take. Then the lecture resumes.

Williams won't give up, it seems, until he's won the youngster's soul.

Tangled in Chords

As promised, Pharrell is in his suite at 10 o'clock. After pulling up a chair, he starts loading up the hotel's CD player, looking tired but ready. Right away, he identifies a key theme of the eight remaining cuts.

"All of these songs will get you [sex]," he says, sincerely. "Your girl can't be mad at you when you listen to these songs, because it comes from such a warm and genuine place."

Other themes emerge: Pharrell calls himself a "chord fanatic," and every song here has some progression that sends him into a reverie. He also is a sucker for what he calls "fearless melodies," by which he seems to mean melodies that don't flinch from tenderness or accessibility.

But Pharrell spends much more time singing along to his favorite songs than dissecting them. Each number puts him back in that oblivious zone, and at various points Pharrell's eyes roll back in his head as he listens. Music is his heroin. When he says anything, it's usually just to fawn like a fan.

"This record right here," he says, shaking his head as he introduces the Gap Band's "Yearning for Your Love." The voice of lead singer Charlie Wilson astounds him. "He doubles his vocals at the end, and listen to that [vocal] riff. Got you running in and out of my life. He sings it over and over just to show you he's dope."

Williams marvels, too, at Donny Hathaway, one of the kings of '70s gospel-style soul, who died an apparent suicide at the age of 33.

What do you like about this one?

"The chord changes," Williams offers, when nudged to discuss Hathaway's "Take a Love Song," from an eponymous album in 1971. "And the time signature is great." He's singing again, and you can tell that the commentary part of this exercise, which requires him to stop listening and start talking, is a chore.

He's mesmerized by "Don't Disturb This Groove," by the System.

"The beat's crazy," Williams says of the song. It was a rare hit for the dance-pop duo of Mic Murphy and David Frank, who recorded five albums in the '80s and produced such acts as Chaka Khan and Phil Collins. "That record right there," Williams says, again shaking his head as "Groove" winds down. "Shee-eeesh."

She-eeesh, indeed.

Hey, this won't really work unless you weigh in on these songs, Pharrell. A story about you singing your favorite songs, uh, it won't make much of a story.

"Yeah, okay," he says, sounding resolved. He wants to be helpful.

There's more idol worship when it's time for Michael Jackson's "The Lady in My Life," the last cut on "Thriller."

"This record right here, man . . ." Williams says, newly dumbfounded. "Only had nine songs, and the ninth is a killer."

He notes a chord change he calls "mystic," and then lets slip that he's met Jackson a few times, once at Neverland Ranch.

What was he like?

"He's cool, man. Nice dude."

Nice dude? Hey, how about some detail? Any detail.

What did you guys talk about? Music?

"No. When I get around people like that I don't talk much. I was just in awe."

He apparently didn't say much to Stevie Wonder, either.

"I just told him he's a genius," Williams says as "Golden Lady," from Wonder's "Innervisions" of 1973, plays. He sings along and does a bit of air piano, pointing out key changes as they happen. "Naming a particular song of his is almost insulting because it's, like, what about the rest of them?"

More singing, more symphony conducting. He's then silenced by "Bonita Applebum," a song from the 1990 debut of A Tribe Called Quest, a pioneering trio in the world of alternative rap. Pharrell recalls hearing it and thinking that the course of hip-hop had changed for good.

"When this came out, I didn't care about nothing else," he says.

How come?

"I don't know. I just had an addiction for it."

Asked for biographical details -- where were you when you heard this, and what did it do for your music -- he demurs, or he gets a look on his face that begs, please don't make me tell you something I've already told a thousand people. He punches the CD player again. Earth Wind & Fire's "Can't Hide Love" and Steely Dan's "Peg" are played back-to-back.

"Earth Wind & Fire are the black Steely Dan," he announces. That sounds like the promising start to a bold thesis, but then he hedges. "But not specifically, because they're worlds apart."

What unites them is their "fearless melodies." Williams says that Steely Dan's best material is "gallant and brave. It worked for them."

Then he pauses.

"But it's [messing up] N.E.R.D."

A Rant and a Rave

This is a prelude to a mini-rant, which Williams delivers as he wraps up and gets ready to leave the hotel for a very late dinner. He's frustrated by radio's unwillingness to play N.E.R.D. and he's not too pleased with Virgin, either. He griped about his label a few weeks ago to Entertainment Weekly, telling the magazine's reporter, "I'd love for you to call up Virgin and say, 'I'm from Entertainment Weekly and Pharrell is complaining that you guys are not putting the proper money into [promotion] to let the staff do what they have to do to sell this record.' "

He talks about it even though he told the label he wouldn't. "I promised Virgin I wouldn't go back into it. But there's a guy who's running the label who isn't great with management and personnel. It's not for me to judge, but all I can say is that my project is really suffering."

A Virgin spokeswoman, who asked to keep her name out of it, sounded conciliatory: "It's Pharrell, he's a genius, he's a great singer. That Pharrell has an opinion about the marketing of his record keeps things interesting."

N.E.R.D., Williams admits, isn't an easy radio sell because the airwaves are now niche-focused and the group doesn't shoehorn neatly into any particular format.

"The music is very in between. A Ferrari is not meant to be in suburban areas. It's meant to be in upper-echelon areas, and it's not meant to be driven around the ghetto. There are a lot of things that don't necessarily fit, but some of us don't give a [darn]. We drive our Ferraris wherever we want, and the rest of the world doesn't always understand that. I think I stay true to what I believe, and N.E.R.D. just pushes the envelope."

The phone is ringing. It's his manager, who, like Pharrell, is famished. Williams grabs his jacket and wraps it up on a positive, grateful note.

"I'm just happy to be in music," he says earnestly. "It feels like just yesterday I was watching 'Motown 25' when Michael Jackson moonwalked across the stage. I'm 31, but in my mind I'm still a kid. It's a dream come true. I just did a video. I got a Grammy this year."

He's shaking his head again.

"I love it."

Pharrell Williams says his favorite songs "take you on an emotional ride."Williams, here performing in March in Las Vegas, says his influences include Michael Jackson and Steely Dan, right.