The Duplass filmmaking brothers have turned sibling rivalry into an extreme sport for "The Do-Deca-Pentathlon," hitting the brother-lode with this fractious comedy about two sibs settling old grudges. Although co-writers-directors Jay and Mark insist it is not autobiographical, the filmmakers show an uncanny feel for what the growing pains between brothers can look like and how the bruises can linger.

"Do-Deca" is a small film and very much a return to the Duplass' indie roots ("Baghead," "The Puffy Chair"). The movie is populated by friends — the brothers count stars Steve Zissis, Mark Kelly and Jennifer Lafleur among their closest. Director of photography Jas Shelton, a frequent collaborator, shot it. Despite all that love, "Do-Deca" can't always overcome the sensation that this is as much a no-budget as it is a no-holds-barred affair. But the sardonic slights and crafty insights are steadily there. Thematically, "Do-Deca" continues the Duplass tradition of taking on the trials of family relationships. Romance was on the line in their excellent 2010 hit, "Cyrus," which followed Jonah Hill as a slacker son trying to derail his mom's new love. Their more polished but less fun "Jeff, Who Lives at Home," which starred Jason Segel and arrived this spring, was also a story of a slacker, and his brother, and his mother. It's the competitive juices between boys that continue to boil 20 years later that are preoccupying the filmmakers at the moment.

"Do-Deca" is set in the New Orleans suburb where the Duplasses grew up. The film's brothers — Mark (Zissis) and Jeremy (Kelly) — tried to settle their feud years ago. In 1990, their homegrown pentathlon pitted the teens against each other in 25 events that tested their persistence as much as their athletic prowess and included pool, ping-pong, arm wrestling and holding their breath under water. Until Dad stepped in and stopped it. A win would have declared one brother "the best."

That unfinished business has haunted younger brother Mark for decades. As the film opens, he's in a bathtub, depressed and debating whether to head back home to celebrate his birthday at Mom's (Julie Vorus) or take a pass since Jeremy might show up. His wife, Stephanie (Lafleur), is trying to be supportive and son Hunter (Reid Williams) is bored.

Soon the die is cast, Mark and family do go to Mom's, Jeremy does show up, and the unofficial sport of sniping across the dinner table sets in. A random reference to the Do-Deca of their youth sows the seed for disaster. No one, except the brothers, thinks a rematch is a good idea, so naturally, that is exactly what ensues, but covertly.

The brothers are about as stealthy in their stealth as they are in their rivalry. It makes for a lot of madness — the ping-pong death match is a hoot. Since games like this are rarely just games, there is collateral damage to contend with too. What the Duplass brothers have managed to muscle into all that overwrought activity is a film that looks pretty smartly at just how hard it can be to suppress the little resentments that build between siblings over a lifetime. And how helpless the rest of the family is at defusing them.

None of the actors is a household name, though they should be. Lafleur is terrific as Stephanie, trying to help Mark find an identity not defined, or minimized, by his brother. But it is the brothers themselves, so ably embodied by Zissis and Kelly, that make "Do-Deca" such a worthy fight.

Kelly has one of those great faces that wear arrogance and agony equally well. Zissis carries the weight of a younger brother still trying to prove himself in the slump of his shoulders and the fog of disappointment so often in his eyes. Watching Mark's emotional center shift as he goes for his "Rocky" moment is one of the film's funniest and most damaging bits.

Fortunately, it's family, so all will be forgiven. Either that or there will be a rematch.

'THE DO-DECA-PENTATHLON'
Director: Jay and Mark Duplass
Cast: Steve Zissis, Mark Kelly, Jennifer Lafleur
Rated: R, language
Length: 87 minutes
Playing: Pickford
Saturday-Wednesday: 9:00 PM