She didn’t have a dress made of raw meat, an army of pop-locking storm troopers, not even a trapeze. At DAR Constitution Hall on Tuesday night, Janet Jackson had something way better: a guy with a mop.

He dutifully squeegeed the stage during Jackson’s costume changes, soaking up the puddles of sweat that came splashing off the 44-year-old pop star during her 90 minutes onstage.

Go on, Janet. Let ’em see you sweat. Because in a 21st-century popscape where concerts are driven by spectacle, we need to know that beneath all of the sci-fi costumes, strobe lights and Auto-Tune, we’re still witnessing a performance by the living, breathing, profusely sweating human being whose name is stamped on the tickets we just emptied our wallets for.

On the road for the first time since 2008, Jackson’s “Number Ones: Up Close and Personal” tour made good on its title, with the singer delivering a panoply of chart-toppers for a cozy crowd of 3,000. (She’ll perform at a sold-out Constitution Hall again on Thursday after taking Wednesday night off, presumably to catch her breath.)

Fans knew what they were in for — the hits! — but Jackson kicked things off Tuesday by making some of her sweetest tunes feel severe. Hits a quarter of a century old, including “Pleasure Principle” and “Control,” remain forever fresh­­, but she played them taut and tough, executing tightly scripted choreography in a gunmetal bodysuit, her closely cropped hair slicked back tight against her scalp.

As harsh as it looked, Jackson’s best songs were beams of melodic sunshine twisted into tight, springy coils. “Escapade” and “Love Will Never Do (Without You)” — the twin highlights from her 1989 pop masterpiece “Janet Jackson’s Rhythm Nation 1814” — managed to keep their carefree charms, even as Jackson delivered them with clenched fists.

In fact, the more blissful the hook, the tighter she wrapped the song around her — somehow squeezing the breezy sensuality out of “That’s the Way Love Goes” without suffocating it. And she danced emphatically throughout.

Cue mop guy. Sweat was pouring off Jackson from the moment her stiletto boots click-clacked onstage. During the opening thump of “Nasty,” she flung her head back, sending a stream of perspiration toward her drummer’s kit. During pillowy ballads “Nothing” and “Let’s Wait Awhile,” it dripped off her elbows like a leaky faucet.

You couldn’t hear the droplets pitter-pattering onto the stage, but for one of pop’s surviving superstars, the concert still felt in­cred­ibly intimate. Last time Jackson was in Washington, she performed at the relatively cavernous (but not quite sold-out) Verizon Center. Since then, the concert industry has gone into a tailspin, with big-name artists playing smaller venues on tighter budgets.

That felt evident on Tuesday. Jackson’s backup dancers were few and not the best, and the outfits looked like a Black Eyed Peas Halloween costume set. (None of it malfunctioned.)

But if you paid to hear Jackson sing, you certainly got that. Not a single word appeared to be lip-synced. And even at its breathiest, that delicate voice hasn’t lost the laserlike precision that seems to be a part of the Jackson family DNA.

This is Jackson’s first tour since her brother Michael’s sudden death in the summer of 2009, but during her mostly banter-less set, she didn’t mention his name. Instead, portraits of big brother and kid sister appeared on a large video screen during the set-closing “Together Again.”

“Everywhere I go, every smile I see, I know you are there smilin’ back at me,” Jackson sang, now clad in white.

With so many people eagerly cashing in on the fallen pop star’s legacy — from the shoddy 2009 concert documentary “This Is It” to the posthumous leftovers album “Michael” — it was both a joy and a relief to see someone finally pay tribute to the King of Pop with such quiet grace.

Janet Jackson performs at DAR Constitution Hall on Thursday. The concert is sold-out.