A year ago, drummer Matt Helders admits, no one in Arctic Monkeys was thinking, "I bet we'd look good on the pop chart."

But in October, the Sheffield band's debut single, "I Bet You Look Good on the Dancefloor," entered the British pop chart at No. 1. An anthemic punk-pop song addressing romantic frustration and nightclub rituals, it crushed the comeback single by Robbie Williams, England's biggest hit maker of the past decade.

And when "Whatever People Say I Am, That's What I'm Not" was released in January, it became the fastest-selling debut album in British history. First-week sales were 360,000; the previous record holder was Hear'Say's 2001 "Popstars" with 307,000, not surprising for an album featuring a group assembled on "Popstars," the popular British show that spawned "American Idol."

But the notion of an underground band doing it -- and with opening-day sales of 118,500, outselling the rest of the top 20 albums combined -- was staggering.

"No, we had no idea about all that stuff," Helders laughs from Cologne, Germany, a stop on a triumphant world tour that none of the band members (Helders, singer-lyricist Alex Turner, guitarist Jamie Cook and bassist Andy Nicholson) could have imagined six months ago. Stateside, the tour that brings Arctic Monkeys to the 9:30 club Monday sold out quickly.

"People rise to fame and come to it pretty quickly over here," Helders says of being England's latest rock sensations. "We don't take it too seriously, but we do talk about it. We've done a lot already, achieved much more than we expected to achieve. It's not the end of the world if it doesn't last forever."

That could be why the musicians -- two are 19, two 20 -- still live with their parents amid a rise to stardom considered fast even by the hyperspeed standards of modern pop culture. Even the record industry and the media, mainstream and music press alike, have had to play catch-up.

Witness: The band built a vast virtual fan base before getting a record deal, giving CD-Rs of demos to kids who came to shows; those fans in turn posted and swapped them on the Internet. As a result, Arctic Monkeys packed their live shows with fans who knew their songs by heart. Eventually, their grass-roots success caught the attention of major record labels, of which many came a-wooing (inspiring the pithy "Perhaps Vampires Is a Bit Strong, But . . . ").

Last June, the band signed with hip indie label Domino (home of last-year's buzz band, Franz Ferdinand). Soon, the British media, especially the hyperbolic music press that sees itself as the trend-setter and taste-maker in pop culture, were on the case. NME (New Musical Express), slow to the band, made up for it by putting Turner at the top of its "cool list " for 2005 and naming "Whatever People Say I Am, That's What I'm Not" the fifth-best album of all time -- the week it was released. A first-week sales boom was inevitable.

"By then, people had written so much about us that they couldn't not like us," Helders suggests, "whether that's a wrong reason or not. If you have that much hype, you might fall on your ass. All we have to do is just live up to it."

What's likely to help the band live up to the hype is Turner, a genuinely precocious lyricist who is being labeled the voice of a generation (which may explain why he has stopped doing interviews). Turner is blessed with an eye for vivid detail, an instinct for lyric and melodic economy, and empathy for his adolescent peers. His songs are about not getting into nightclubs, losing girls to a cooler guy, being harassed by the police, alcohol-fueled fights -- snapshots of provincial ennui in a working-class northern town. The Guardian dubbed it "social-realist rock."

All this began four years ago when Turner and Cook, then 16, received guitars for Christmas. A year later, they had hooked up with Helders and Nicholson.

"We'd all been friends forever, and me and Alex went to the same primary school from about 5 years old on up," Helders says. "Had no idea about drums, just did it as an experiment. When we started, it was just a hobby, we didn't expect anything from it. It was just something different to do rather than hang about out on the street."

The quartet's first performance in 2003 was mostly covers. As an original sound came together, there were varied influences, mostly contemporary (Franz Ferdinand, the Libertines, British hip-hop acts such as the Streets and Roots Manuva), regional (Manchester's Smiths and Oasis) and local (Pulp, with Turner compared to that band's astute lyricist, Jarvis Cocker).

According to Helders, "When we first started, the Strokes were just coming over to England and getting a lot of exposure, and it was bands like that that kind of made us play guitar music."

As songs written by Turner began replacing covers, Arctic Monkeys started giving away the CD-Rs that ended up on the Internet. They were hardly pioneers in viral self-exposure: Bands such as America's Clap Your Hands Say Yeah and England's Libertines had already figured out how to connect with a new generation of fans who had never known music without the Internet.

Says Helders: "We encouraged [fan postings] as much as we could because we never expected to make money off of demos. We didn't have a CD, but people wanted to hear the songs and it made our gigs better. We wouldn't be here now if that hadn't happened to us, so we're definitely thankful about that."

The band took its name from a list of fantasy soccer teams and bands that Cook had made up in school, but the album title comes from Alan Sillitoe's 1958 novel "Saturday Night and Sunday Morning," a key work in the '50s school of British writers dubbed "the angry young men," who wrote about other young men trying to escape their dreary, working-class lives. Last year Domino Records founder Laurence Bell gave them the DVD of the 1960 film version that made a star out of Albert Finney as womanizing factory worker Arthur Seaton.

"When we watched the movie, there was a familiarity to it," Helders says. "I've got the book now -- haven't started reading it yet -- and we got a letter from the author yesterday, saying that he liked the album and he was privileged that we'd used something from his book."

"Saturday Night and Sunday Morning" seems to have shaped the sequencing of songs on the Arctic Monkeys album. It's something of a concept album, following one character's weekend adventures of clubbing, chasing girls and dodging bouncers and police alike.

"It's not like we're trying to tell people about their own lives," Helders says. "We're just singing about what we've experienced, which in turn are things that a lot of people have experienced. I think that's why they can relate to it."

How all this will play in America is open to question, particularly since Turner makes no accommodation for his thick Yorkshire accent and lyrical slang. So far, both American media attention and label exploitation have been minimal, though the band did manage to score a slot on "Saturday Night Live" on March 11. Their album, released here Feb. 21, debuted at No. 24 with 34,000 copies sold, less than one-tenth of its first-week numbers at home. At the South by Southwest music conference in Austin last week, Arctic Monkeys was one of the hardest-to-get tickets, and they were Topic A on the panel "Breaking British Buzz Bands."

Clearly, buzz works: Arctic Monkeys' first full-fledged American tour sold out in minutes.

Says Helders: "It's more of a boost in confidence, knowing that people want to come and see us, unless they come and see us and decide they don't like us. It's something we're enjoying more than anything, not feeling any pressure. We're just taking it as it comes."