The action-hero deficit has grown so pronounced in Hollywood over the last few years that the unlikeliest actors are being pressed into combat, including, most recently, 56-year-old Liam Neeson in Taken.

Enough of this charade. The silver screen is crying out for a real macho man.

Calling John Cena. Calling John Cena. Please report to the film set.

The larger-than-life - and larger than damn near everything else - pro wrestler stars in 12 Rounds, opening Friday. He plays a New Orleans cop who, in order to save his girlfriend, must complete a series of impossible challenges set for him by a psychopath.

It's actually Cena's second film, but 2006's The Marine barely counts because it was a baptism of fire, ignited by Vince McMahon, chairman of World Wrestling Entertainment.

"The Marine was a script that was written for [wrestler Stone Cold] Steve Austin. But he just wasn't on good terms with the WWE at the time," says Cena, 31. "It was already in preproduction. They were set up and ready to shoot. They needed a guy and my boss [McMahon] said, 'Hey, you're going to do this movie for me.' That was my introduction to the world of acting."

The three-time WWE champ is aware of his limitations as a thespian.

"Right now, anything outside something I can draw real-life inspiration from would be a real stretch for me," he says. "I wouldn't be able to do a western or a period piece. I don't have that ability. I really have to work on the fundamentals of acting."

Renny Harlin, the Finnish-born director of 12 Rounds, did everything in his power to make his inexperienced leading man comfortable.

"I told John and the rest of the cast that I'm shooting this film in a guerrilla way," says Harlin on the phone. "I'm going to have three cameras running the whole time, covering the scenes from all angles. I even shot the rehearsals like that.

"I did that so John didn't have to think about hitting his marks or positioning himself for the lighting. I didn't want him to have to worry at all about the technical stuff."

Shooting on location in New Orleans, Cena also maintained his demanding schedule as one of the stars of Monday Night Raw on USA.

"I would work all day Monday until about 4," says Cena, "take a charter to where Raw was. Get there just as we were going on air at 8 or 9 o'clock. Change into my gear, do my deal, and charter back to New Orleans about 11 o'clock."

Because The Marine was shot in Australia, Cena was forced off the wrestling circuit for a few months. With typical over-the-top showmanship, the WWE announced he had been stabbed in the kidney at a Boston nightclub by the bodyguard of ring villain Carlito Caribbean Cool.

A fabrication? "Absolutely," says Cena. "That was completely entertainment." The raised scar on his neck is real, however, a remnant of recent ring-related neck surgery.

Cena is sitting in a room at the Ninth District police precinct on North 22d Street. Looking like an impossibly pumped-up version of Matt Damon, he has a discomfiting presence. His military-style flattop and armor-plated frame imbue him with an air of menace even when he is relaxed and smiling.

He's just finished signing movie posters for a long line of officers' children. You've never seen so many people with holsters jumping around, popping pictures with their cell phones held at arms' length.

Even seated, at 6-foot-1 and a steely 250 pounds, Cena tended to dwarf all the autograph seekers.

"I think I have the physique of an athlete rather than a bodybuilder," says the actor.

Actually, he has the build of three athletes welded together, with biceps the size and consistency of fireplugs.

Those ginormous guns are covered up in almost every scene in 12 Rounds.

"It's by design," says Cena of the camouflaging wardrobe. "Because the movie is about an everyman put in an extraordinary scenario. It would be difficult for the audience to grasp if you see a guy on screen who appears to be superhuman.

"It's tough to put actors next to me that would compare. The leading villain [in 12 Rounds], Aidan Gillen, is 5-foot-6, 140 pounds. Those matchups don't look right on paper, and immediately the consumer thinks, 'OK, this movie is over. He should stomp that guy.' "

Stomping has been part of Cena's repertoire since he was a boy in West Newbury, Mass., the second of five strapping brothers.

"We all have the same bone structure," says Cena. "Every one of us wears a size 13 shoe and has got a fist that will knock you out with one punch."

The brothers ran in a pack. "We were some hellions," he says, his eyes lighting up at the memory. "Good times, growing up. Lots of broken furniture, lots of broken bones, lots of destruction."

Perfect training for a pro wrestler.

A college football star, Cena pursued bodybuilding before joining the WWE circuit in 2002. He adopted a hip-hop persona, performing freestyle raps before matches and releasing an album, You Can't See Me, in 2005. His signature moves in the ring include the Killswitch and the Five Knuckle Shuffle.

Even with Cena's block-of-granite build and athletic reputation, there are still guys who step up to challenge him in public. Usually guys who have had too many cocktails.

"I certainly have run the gamut of meeting people who want to fight," he says. "Maybe you're out locally in a bar. They're serious and you're not. Usually a good talking to is enough. If somebody doesn't cool down after that, you just leave."

As Cena moves into film work, one of the challenges is finding someone big enough to serve as his body double.

Fortunately, he does most of his own stunts. That came back to bite him in 12 Rounds.

"He's petrified of heights," says costar Ashley Scott, the film's damsel in distress. "And we were jumping out of helicopters and climbing out of tall buildings. He did his best, but you could kind of tell he was deathly afraid."

"I was hanging from a 10-story building with only a harness," says Cena of one scene, his muscle-bound jaw knotting. "They shot it with the camera pointing down so you can see there's no net. Seriously, I still get shaky thinking about it."

Other than that, how'd you enjoy your second foray into filmmaking?

"I was made to do stuff like this," he says. "It was right down my wheelhouse. It was a John Cena fastball."

Swing for the fences, Slugger.