What's a maturing boy band to do? If you're the Backstreet Boys, it's sadly, painfully obvious: Loathe yourselves. As we saw at this year's Super Bowl, where they sullenly crooned the national anthem, the Boys are in a slump, and last year's soggy ''Black & Blue'' reflected it (case in point: AJ McLean's recent behind-the-music moment). For their arch-rivals 'N Sync, who seemed thrilled to be onstage at the halftime Super Bowl show, the answer is diversify, diversify, diversify. Either to show off their eclectic tastes or to ensure that they have a future on one radio format or another, 'N Sync have stuffed Celebrity with as many genres as there are songs. So let's analyze this pivotal -- for them -- album, cut by cut:
''Pop'' The disc opens with a jolt of jittery pop-techno, and there's an undeniable oomph when those bustling beats kick in on the chorus. But it's producer Brian Transeau, a.k.a. BT, and not cowriters Justin Timberlake and Wade Robson (a.k.a. the band's choreographer), who is clearly the hero. The paranoid lyrics, in which they congratulate themselves for ''the gift of melody,'' are obvious at best, self-glorifying at worst. Still, the single's blend of beats and bad attitude should have Michael Jackson very worried. B+
''Celebrity'' ''If I wasn't a celebrity/Would you be so nice to me?'' they grumble on this whirring Rodney Jerkins-produced thumper. About a year ago, I predicted that the teen boom would end when its practitioners started writing their own material. Let me revise that: It will end when they start writing their own material about how hard it is to be rich and famous. C+
''The Game Is Over'' Their troubles continue -- this time, at the hands of a woman who dispenses ''lies.'' Lesson of the album so far: It's not easy being a guy, even if you're in 'N Sync. The music is pure PlayStation pop -- it even samples Pac-Man -- but they sure know how to sink their pearly teeth into a PO'd chorus. B
''Girlfriend'' Timberlake puts the moves on a young thing by giving her the old ''I'm better than him'' line; Jacko's heyday is again invoked by the chunky-funky groove, courtesy of in-demand producers the Neptunes. Bonus point: The song is far less obsequious than the faux-R&B moments of ''No Strings Attached.'' B
''The Two of Us'' Picture yourself with a ''Lucy in the Sky With Diamonds'' riff fused with happy-face two-step -- and then made trite by lovestruck lyrics (''I'm thinkin' 'bout you day and night/And I just can't get you off my mind''). B-
''Gone'' Yet another example of the band grabbing the reins of their own music, this Timberlake-Robson cut has the sparest production so far: a basic thump, some flamenco guitar, a jab of strings, a ghostly whisper of a chorus, and a trembling-vibrato delivery recalling ''Off the Wall.'' No wonder Jacko supposedly wanted it for his upcoming album. Then again, maybe he shouldn't bother finishing it: ''Celebrity'' might as well be the next Michael Jackson record. B-
''Tell Me, Tell Me...Baby'' Europop craftsman Max Martin returns with his ellipses (''Baby...One More Time''), and not a moment too soon. Assembled in Sweden, this is a fallback in case the experiments fail, but as fallbacks go, it's a good one. B
''Up Against the Wall'' JC Chasez, the most adventurous member when it comes to both music and hair, dips deeper into two-step. The beats zigzag like mad, matching the lyric about cruising a club at night and doing, well, something against a wall with an enticing female. First reaction: Who'd have thunk it? Second reaction: What exactly do the blond one, the chunky one, and the one with the goofy broom-handle hair do in this band? A
''See Right Through You'' The third consecutive dance cut, this one another tale of betrayal by scheming girls. Timberlake's huffy, teeth-clenched delivery is, again, vintage Jackson. As for the lyrics: ''Does he freak you the way that I do?'' -- well, JC, you're no Rick James. B
''Selfish'' Target: the adult-contemporary market. Ammo: producer Brian McKnight, soppy lyrics, and the dusting off of the Croon, a boy-band staple. The Backstreet Boys could take this to a higher plane; 'N Sync settle for competence. B
''Just Don't Tell Me That'' Like ''Tell Me...'' this, too, feels like a leftover Ace of Base track that one of their team of Swedish producers stuck in the mail. That doesn't make it any less propulsive. A-
''Something Like You'' Another hallmark of the boy-band era: the squishy ballad with drooling-puppy harmonies and lyrics (''You must be heaven-sent, I swear''). Should have been banished to a 98 Degrees album. D
''Do Your Thing'' Mild electronica, willowy vocals -- they've now morphed into Janet Jackson. Pleasant filler and nothing more. B
Which, come to think of it, is the average grade for the whole album. ''Celebrity'' may be the consummate teen-pop experience: It has the R&B swipes, the ballads, the grasps at artistic self-expression, and the requisite Europop. On it, 'N Sync are both puppets and puppet masters. Even if it all crumbles (the muted reception to ''Pop'' is ominous), they'll go down swinging. As the Backstreet Boys are proving, there are more troubling fates for boy bands.
