Thirty seconds into track one, and anybody who ever cared about Liz Phair knows something's up. Before she gets to be coy or clever, the formerly acid-tongued indie-rock siren, now 34, can be heard proclaiming "I'm extraordinary" over a bargain-basement teen beat that sounds like an Aguilera reject.

And she doesn't just make the claim once. No, Phair begins her eponymous release by insisting on her specialness again and again and again, as if she's trying to convince herself.

Thus begins one of the saddest chapters in the short history of alt-rock, the cautionary tale of a smart, influential artist who, after critical acclaim but dwindling sales, chose to take a stab at commercial pop. It could have been a cheeky move. Instead, "Liz Phair" (Capitol, 1 and 1/2 stars out of four) -- the singer's first CD in a half-decade -- is a spectacular career spinout, a car wreck in 14 torturously labored segments sure to leave devoted supporters wondering, "What was she thinking?"

Phair didn't just dip a toe in. She spent years in the studio following the formula for countless current radio songs, everything from the insinuating mini-melodies to the smacking snare drum sound. She wrote brainless singsong odes that might interest the copyright lawyers at Toon Disney. She even hired the Matrix, the British songwriting-and-production operation that put those gnarly words into Avril Lavigne's mouth.

And when it came time for photos, Phair tarted things up, entering herself in the Willa Ford-Britney Spears soft-porn sweepstakes.

Here's what she got back: a set of shrill, desperately oversexed and cynical songs built to code, but completely hollow on the inside. It's as though the divorced single mother set out to erase every bit of goodwill lingering from her 1993 full-length debut "Exile in Guyville", the proudly lo-fi collection of bitter post-love songs that became the rallying point for riot grrls everywhere.

"Liz Phair" is "Exile's" corporate evil twin: prissy where the former was unkempt; eager to please (or seduce) where the former was fueled by don't-give-a-damn irreverence; packaged, anthemic and in-your-face where the former was assertive, category-free and quietly sultry.

While it's disappointing to see Phair so easily turn her back on her former direction, what's more troubling is how willingly this once-defiant songwriter has slipped into the generic slutgear wardrobe, and how easily she has relinquished her sonic identity to do it.

Compare just the melodic material on "Exile" or its follow-ups -- 1994's "Whip-smart" and 1998's "whitechocolatespaceegg" -- to the new work and you discover that Phair has whittled down her once-flamboyant extended lines to fit pop's repetitive four-measure template. You hear Phair prattle near-tunelessly about how a particular lover is like her favorite underwear, on the Matrix-produced "Favorite," and wonder, is this the same composer whose pensive "Explain It to Me" brilliantly tiptoed between consonance and dissonance, whose "Stratford-on-Guy" elevated three basic notes into music of thundering, near-orchestral resonance?

Asked about this, Phair said last week that she's always listened to radio songs. "It got me into trouble during 'Guyville', actually. I was cynically capitulating to indie music to pretend I didn't know the words to 'Jack and Diane'."

Making records involves all kinds of compromises, and one was Phair's decision to collaborate with the Matrix -- the threesome that's worked with the Backstreet Boys, Britney Spears, Nick Carter, Ricky Martin, Lavigne and many others. Though the Matrix songs -- the overwrought "Extraordinary", the insistent anthem "Why Can't I?", the carnal twins "Rock Me" and "Favorite" -- aspire to Avrilian intensity, none comes close. Instead of exuding sexual heat, their age-inappropriate harlotry is an embarrassment -- one that makes you wonder if Phair is having a midlife crisis.

Alas, Phair's other collaborations -- including five written with Michael Penn that are only marginally more adventurous, as well as the songs she composed alone -- are no more successful. Of the latter, one, "H.W.C.", will get attention primarily for its explicit lovemaking play-by-play.

Phair says she's not only proud of the CD, but that she looks forward to performing the tunes she wrote with the Matrix because they're "exciting" and "joyful". She concedes that during the making of the record, Capitol wouldn't pony up any more money unless she did something like a Matrix collaboration, something the label thought would guarantee a "return" on their investment. But she understood their mind-set.

"I wanted to be able to get another ride" after the current CD, Phair explains. "I didn't think of it as giving up myself to please the man... I thought it was very indie of me, and smart, to take advantage of the opportunity so that I can keep making records."

It's part of the survivor mentality that's always guided her, she says proudly: "I move through my circumstances and do what I need to do next."

Even, apparently, when that means telling everybody she's extraordinary instead of actually being extraordinary.