NEW YORK — Even someone like Brad Pitt — the $20-million-a-movie man, one-half of Hollywood's platinum couple — has his weak spots.

There's that tendon in his heel, the one he hurt after months of pounding the sands of Mexico and Malta during the Troy shoot, the one that's named for Achilles, the very man he plays in the celluloid epic about the Trojan War. "Stupid irony," Pitt mumbles dismissively. Judging from his strong gait, he's healed

He and his Greek warrior character share another vulnerable site — the heart (after all, love, as much as an arrow to the heel, ultimately brings down Achilles). When it comes to intimacy and emotion, "the more you put yourself out there and open yourself up to that, the more you risk being hurt," Pitt says. "That's probably true for most of us."

But there's yet another place where Pitt is susceptible these days. Though his nearly four-year marriage to Jennifer Aniston appears solid as they try to have their first child, some say Pitt's matinee-idol status is being tested with Troy, opening May 14.

At a reported $200 million, it's not only Pitt's biggest movie ever "in budget, scope and scale," he says; it's also one of Hollywood's, in the company of Titanic. And for Pitt, Troy is arguably fraught with titanic expectations.

Pitt, 40, hasn't starred in a film that grossed at least $100 million in nearly a decade, since 1995's Seven (2001 hit Ocean's Eleven was a true ensemble film). Though Troy features a cast of stars including Orlando Bloom and Peter O'Toole, Pitt carries the weight of the epic on his tanned, muscled shoulders.

Since he bared his abs in 1991's Thelma & Louise, Pitt has successfully zigzagged between riskier material such as Twelve Monkeys and commercial fare like Ocean's Eleven.

In Troy, Achilles must make a decision: fight for the Greeks in their quest to recapture Helen and their honor from Troy, or stay home and raise a family — in other words, achieve lasting glory but almost certain death, or settle into anonymity.

What Troy means for Pitt's career as a leading man is uncertain.

"I don't think it's wrong to say there's a fair amount riding on this movie. And he is the main attraction," says film critic Leonard Maltin, co-host of TV's Hot Ticket. "But I think he has much to gain here, because we haven't seen him in this kind of heroic part." And film studio Warner Bros.? "I think they bet on the right horse."

Pitt, though, is positively blasé about the pressure. Whether it's an edgy, arty flick like Fight Club or an aspiring blockbuster like Troy, the moviemaking process "still feels the same to me," says Pitt, sitting in a Midtown hotel suite.

You put everything you can into it, and some work, some don't. I think this one's really strong."

Physically, Pitt prepared for the role with a year of intense training. "The first three months were daunting and not fun at all." It included two to three hours in the gym, two additional hours of sword work and four high-protein, low-carb meals a day. As a result, he gained about 10 pounds of brawn. "It was grueling," Pitt says.

Giving up beer and smokes

He nixed cigarettes and sharply cut back on beer and chips, although he did allow himself the occasional treat: McFlurry shakes from McDonald's, "though it was more for a little taste of home, you know, a little Americana."

Pitt tries to shrug off the emphasis on his body-building. Transforming himself into the arrogant and aloof ancient warrior had its cerebral component, too.

Among other research, Pitt dived into The Iliad for the first time. (He jokes that he had to because journalists would quiz him on it.) "I was surprised. It wasn't a task at all. I really enjoyed it. There's a reason it is what it is."

Director Wolfgang Petersen, best known for showing the underbelly of U-boat life in Das Boot, stresses that a buffed-up Pitt was "extremely important."

"You cannot have Achilles with a pot belly. That doesn't work. He should not only fight like an artist, but he should look like a god."

There were other, um, behind-closed-doors benefits, akin to what Will Smith said he experienced when he pumped up to play Muhammad Ali in 2001's Ali: "My wife's loving it."

Pitt flashes a broad, dimpled grin. "I'm going to agree with Will. There are certain advantages to the hard work. There is a payoff."

Slacking off, though, began the day Troy wrapped, says Pitt, fresh from a pre-interview cigarette break. "Propped up on caffeine" and popping chocolates into his mouth, he's alternately rubbing the knuckle above his wedding band and tugging on his earlobe, looking more Ocean's Twelve than Troy in slacks and a gray-and-white striped shirt, unbuttoned slightly to reveal a silver chain necklace.

But back to burgers and pizza
Says Petersen: "Achilles is such a huge name. To play a part like that, for every actor that must be a little intimidating. There's a lot of scrutiny going on here, and he did it really well.

"A lot of people are surprised to see Brad doing a part like this. But for me, it was not at all a stretch."

Considering his roles as the Irish drifter Mickey O'Neil in Snatch and the nihilistic rebel Tyler Durden in Fight Club, "there were indications that he had that dark side to him as an actor."

As the director of Fight Club and Seven, David Fincher helped reshape Pitt's image as a beefcake from meat-and-potatoes Missouri (though there's at least a calendar's worth of Pitt pinup shots in Troy).

Fincher likes the irony of a subversive Tyler and a tormented Achilles "being played by People magazine's favorite cover child." Pitt and Aniston each have been named to the magazine's 50 Most Beautiful People in the World list four times, including this year.

"There's something to be said for choosing roles in which you get to play people that you aren't," Fincher says. Pitt is an "extremely polite guy, yet he doesn't play polite characters."

The polite-guy tag is echoed by many. Simon Kinberg, writer and co-producer of Pitt's upcoming Mr. and Mrs. Smith, calls him "one of the most grounded, down-to-earth people I've met." Pitt repeatedly offers a visitor a drink, chocolate, even room service.

No prima donna

"He could just be the prima donna of them all, and he's not," Petersen says. "I don't think he's a born superstar. That's what he is, but I'm not so sure that's what he wants to be."

The accidental A-lister attitude is part of his allure, says Maltin. "You hear more about him than you hear from him," Maltin says. "And that creates a bit of a mystique."

Pitt's spotlight is so bright that even an A-lister like buddy and Ocean's co-star George Clooney says he stands in his shadow.

Fans "step over you to get to him," Clooney says. While in Turkey for the opening of Ocean's Eleven, Clooney walked in first, and "everyone starts screaming, 'George!' I said, 'Hey, Brad Pitt!' " The crowd turned and swarmed his friend. "I was his bodyguard at that point," Clooney says.

Clooney has only one bone to pick, namely Pitt's height: "He's tall. He's like 6-1. It's irritating." At 5-foot-11, Clooney says, he looks like "the little guy."

Then there's his lantern-jawed, lifeguard-cum-military-man looks, including those eyes that are as blue as the Aegean Sea.

"He's a little ugly," Clooney deadpans. "He got hit with an ugly stick." Pitt, who's a couple of years younger than Clooney, "looks a decade younger than me. He's sort of a genetic freak."

Pitt is poised to pass on some of those good genes, and not just the physical ones. "I feel like I know enough now where I can be responsible and lead someone through, instead of, you know, screwing them up too much," he says.

He's confident that his schedule, jammed with Mr. and Mrs. Smith and Ocean's Twelve after a relatively calm couple of years, won't interfere with parenting.

Of Aniston, who has now wrapped NBC's long-running Friends, he says that "we get our time; we really carve out time for us."

Meanwhile, as Friends approaches its finale on Thursday, Aniston has signed to star in several films, including a remake of the 1966 British caper Gambit.

The couple are making movies through their production company, Plan B. But don't expect to see them act together anytime soon.

"You look at past case studies of couples working together in films, and the odds are really against us. You know what I mean?"

Well, he doesn't mean Gigli, the flop that signaled the demise of Hollywood's formerly platinum pair, Ben Affleck and Jennifer Lopez.

"I actually liked Gigli. I thought (the criticism) was unjust and more of a response to the oversaturation in the media. Affleck did some really great stuff in there."

Even as the headlines scream "Brad and Jen" instead of "Bennifer," Pitt seems unfazed by the tabloids and celebrity magazines that pursue him and Aniston relentlessly.

"That's what I get for stepping in the ring," he says. "I spent the first few years fighting it. It just takes up so much of your life, you miss your life almost. And it rarely has any basis in reality."

Like the rumor that he wouldn't strap on sandals as part of his Achilles costume for fear of exposing yet another alleged vulnerable spot, his gnarly feet.

Pitt, who wears knee-high boots in the movie, shoots that one down: "I wanted something you could actually fight in."