'INVINCIBLE" is about Philadelphia Eagles fans. So it's another psycho movie?

Sort of. It's (inspired by) the true story of a Philly bartender and Eagles fan named Vince Papale - source of that 5-watt pun in the title - who was crazy enough to seek a spot on the team when new coach Dick Vermeil held open tryouts. Papale showed up, ran a 40-yard dash in 4.5 seconds, endured many hits that sounded like what happens when a sack of Cocoa Puffs meets a ball-peen hammer, and made the Eagles as a special-teams man.

His story is disarmingly low-key because of how little happened after that. But that's the strength of the movie. It has grit (in both senses) that lands it much closer to "Rocky" than "Rocky III."

As in "Rocky," we're not only in Philly but also in 1976, before the invention of shampoo. Federal mustache regulations required virtually all adult males to install a Burt Reynolds lip topiary, and women wore shapeless rough-hewn man-shirts. These details make for an excellent atmosphere put together by first-time director Ericson Core. Perhaps he dabbed a rag in Pennzoil and wiped it all over every frame of the film, because the movie is fantastically grubby, all smokestacks and chipped paint, which is pretty much how I remember the '70s.

Core also has the right actor to play Vince. Mark Wahlberg actually looks like a football player - the man was born to star in "Wayne Chrebet: The Movie" - and he is not only tough but working-class, a quality more difficult to fake than actors think.

Elizabeth Banks, as a fellow bartender from New York who likes to show up at the bar in a Giants jersey, is another good choice, friendly and uncomplicated as the girl he meets after his wife leaves him with a goodbye note. We don't know what the note says at first because the director is holding it for a perfect moment, and he's equally good at saving a punch line. The Banks character left her ex because "he wasn't what he said he was." "What did he say he was?" asks Vince. "Single," she replies.

The football scenes are shot with a rib-jangling ferocity, and the real logos (this is only the fourth film to receive NFL cooperation) help make them convincing. What football fan can resist smiling at a glimpse of that stand-up re-set the Cowboys' offensive line used to do?

The writing leans to the obvious and it understates the nastiness of Eagles fans (but you knew that anyway from the PG rating). The worst we are told about them is that "they threw snowballs at Santa Claus." Yeah, and sold his sleigh to the chop shop before they roasted Blitzen over an open oil can. Also, Greg Kinnear wouldn't be my first choice to play the ever-teary Dick Vermeil . . . Jane Fonda, maybe?

But the movie has the lazy summery pace of Elvin Bishop's "Fooled Around and Fell in Love," one of many excellent choices on the pre-disco soundtrack (Bachman-Turner Overdrive, Jim Croce, and where did they dig up "How Long" by Ace?). The relaxed feel is what makes it so likable: This movie is grounded. Vince isn't going to save his country like Seabiscuit, he isn't going to be a hero unless you grade on a curve, and his team isn't going to win the Super Bowl, in this movie or in reality. These are the Eagles we're talking about, the Choking Chickens, the Despair of the Delaware.

Vince is just a guy who wants to make a few plays before he hangs it up, and the movie's centerpiece doesn't even take place in an NFL stadium but in a muddy parking lot where guys play football lit by the headlights on their cars and know they're out of bounds if they get thrown through a windshield. There is an almost military splendor to football, and an almost military tragedy. Few movies know the sport so well.