Mike Flaherty (Paul Giamatti) coaches Kyle (Alex Shaffer), a troubled teen turned surrogate son and star wrestler, in Tom McCarthy’s “Win Win.”

“Win Win” is a family comedy with an unusual list of participants: an actor-turned-director, an Oscar-nominated star, and a 17-year-old Jersey boy with no Hollywood resume. It tells the story of Mike Flaherty (Paul Giamatti), a struggling eldercare lawyer who is desperate to provide for his wife and two young daughters. A former wrestler with a love for the game, Mike coaches high school wrestlers in his spare time. But his team is doing about as well as his practice—he’s short on money and his wrestlers haven’t won a match in years.

Mike sees an opportunity to ameliorate his situation when one of his clients, Leo (Burt Young), is in need of an on-paper guardian for himself; Mike takes on the paying job to score the extra cash. But he’s thrown for a loop when Leo's estranged grandson, Kyle (Alex Shaffer), arrives at his doorstep unaccompanied, looking for an alternative to life at home with his drug-addicted mother. Before Mike knows it, Alex is living in his house and, with newly discovered talent, bringing Mike’s wrestling team out of oblivion.

For writer and director Tom McCarthy, inspiration came from the sport itself. “I developed the story with a high school wrestler, now lawyer, Joe Tiboni,” he said. “We used to wrestle together, we were on the same team … and that’s how this whole idea got started—just joking around about high school wrestling, and how there’s really never been a great high school wrestling movie.”

At the center of the visceral wrestling excitement of “Win Win,” though, is a real family man in the form of Giamatti’s Flaherty, whom McCarthy freely admitted was based largely on Tiboni himself. Like Mike Flaherty, Joe Tiboni is an eldercare attorney who is married with two kids. “There were certain similarities that we were cherry-picking for the story … It was fun for us to take something from Joe’s life, put it in the movie, and see it on set,” McCarthy said.

With its eclectic intergenerational cast, “Win Win” falls right in line with the types of films and characters that McCarthy—who recently helped draft the story for Pixar’s “Up”—is used to writing. “[The characters of ‘Win Win’] are pretty ordinary people who just have unique personalities,” he says. “And in bumping up against each other, they reveal something about themselves.  I’m interested in that—in ordinary people and the kind of extraordinary moments that can be developed between them, stories that could fall between the cracks sometimes.”

Bumping against the well-established Giamatti is the film’s younger star, 17-year-old newcomer Alex Shaffer—a New Jersey native who had no prior acting experience aside from a small role in his sixth grade production of Gilbert and Sullivan’s “The Pirates of Penzance.” His breakout performance as Kyle has earned him great advance critical claim; Deadline Hollywood named him one of Sundance’s “10 Actors to Watch.”

The low-keyed Shaffer characteristically downplays his accomplishment. But though he lightly dubs his “Win Win” experience “very interesting,” there’s no doubt he enjoyed it. Acting is “something completely new to me,” he said. “I loved it. It is something I’m going to keep doing.” Shaffer noted that being a novice may have been beneficial, because it fended off nerves—as a Hollywood outsider, he felt far less pressure than a career actor whose future depended on the film’s success. This carefree attitude carried over to the set. When asked what it was like to work with Oscar-nominee Paul Giamatti, Shaffer replied with blunt honesty: “At the time I didn’t really care ... I didn’t really appreciate it until now,” he said. “It’s so crazy to be in a movie with him, a Tom McCarthy movie … like, holy shit.”

But because Shaffer is so even-keeled, some of the darker sides of Kyle were difficult for him to portray—especially a scene in which he physically confronts his derelict mother. For these moments, Shaffer turned for inspiration to the story of a much-admired musician: Eminem. “[Eminem and Kyle] have such similar lives,” he said, citing their drug-addicted mothers and the release they each found in a particular talent. In acting out this imagined angst, the Hollywood newcomer hopes he managed to do justice to McCarthy’s complex material. To judge by the critical reaction to the actor’s work, “Win Win” and Shaffer both have a bright future ahead in movie theaters.