Sylvester Stallone, star of the film 'Rocky Balboa,' is seen before a premiere of the film in Philadelphia, Monday, Dec. 18, 2006. (AP Photo/Matt Rourke)

"Rocky Balboa," the sixth (and hopefully last) installment in the underdog saga of the Italian Stallion, straddles the line between nostalgia and self-parody and frequently teeters toward the latter.

Returning to his roots, Sylvester Stallone writes, directs and stars once again as the iconic title character, who long ago retired from boxing and now has carved out a quiet life as a South Philly celebrity and restaurant owner. He mourns the loss of his beloved Adrian, who died of cancer, and still hangs out with her loudmouth brother, Paulie (Burt Young). ( Talia Shire appears in flashbacks at moments that ostensibly were meant to be inspiring, but instead just feel clunky.)

But when an ESPN computer simulator pits him in his prime against the current heavyweight champion, Mason "The Line" Dixon (retired light heavyweight champ Antonio Tarver), Rocky gets the bug for that tried-and-true one last fight.

No one thinks he should do it?- not his son, Robert Jr. ( Milo Ventimiglia), who's bitter about the burden of having famous blood run through his veins, and certainly not the media, who have a ball bashing Rocky before he even sets foot in the ring.

This would be an example of art imitating life?- or is it the other way around? The idea of yet another "Rocky" movie writes its own punch lines, and Stallone deserves some credit for being aware of this phenomenon and having enough confidence in himself not to care.

And there is a certain allure to the ritual of revisiting the character, a comfort in the familiarity. He's mellowed a bit now as he wanders about town, incapable of walking down the street without being approached for an autograph, yet he continues to spew those overly simplistic Rockyisms in that rumble of a voice that sounds like he's gargling with marbles. ("You know, you learn a lot talking to dogs" is among the funniest.)

He and Paulie still have that spirited banter in which neither seems to be listening to the other, and he's added a new friend: a shy single mom he knew as a girl from the neighborhood, whom he still affectionately calls Little Marie (Geraldine Hughes), who comes to work as the hostess at his restaurant.

But then when the inevitable training montage begins, to the swelling strains of "Gonna Fly Now," it's all so hard to take seriously after all this time. He does everything you expect to see him do?- he lifts hulking metal chains and kegs of beer, jabs and hooks those giant slabs of meat, before running triumphantly up the steps of the Philadelphia Museum of Art- and does it all with heart.

Lest we forget, as he prepares to get his butt beaten by a man half his age, we are repeatedly reminded of the comparative enormity of Rocky's heart. Tarver's character, meanwhile, is merely impudent and pampered?- so poorly fleshed out, it's hard to care about him at all much less fear or loathe him. It makes you long for the broad charms of Mr. T.

But let's be honest: Was anyone (besides Stallone) really curious to see how Rocky might turn out at age 60? He is in massively muscular, fabulous shape?- truly a specimen to behold at any age — and maybe that's the point after all.

Stallone says he wanted to close out the franchise with a sense of satisfaction after the bomb that was "Rocky V" in 1990. But maybe he also wanted to stand there covered in fake blood and sweat, wrapped in a silk robe, and revel in the warm glow of having an entire arena full of extras chant, "Rocky! Rocky!" one more time.

Back in 1976, it all seemed so inspiring; the original "Rocky" was a small gem that became the surprise best-picture Oscar winner. In 2006, though, "Rocky Balboa" merely feels like a shameless vanity project.

"Rocky Balboa," an MGM Pictures release, is rated PG for boxing violence and some language. Running time: 98 minutes. Two stars out of four.