FOUNTAIN VALLEY, Calif. -- A young Australian is almost single-handedly spurring a new age in bowling: He throws the ball with two hands.

With an easygoing charm to match his spiky brown hair and rock-star sunglasses, 25-year-old Jason Belmonte, bowling in a tournament here this week, could well reach new audiences for a sport many younger Americans associate with "The Big Lebowski" and beer bellies.

He has quite a novel delivery. Rather than use one hand, he shovels it forward with both from the right side of his body as he slides to a stop at the lane's foul line. Mr. Belmonte plugs two fingers, but not the thumb, of his right hand into the ball's holes and uses his left hand to create extra spin.

The ball can top 600 revolutions per minute, up to 17% more rotation than the nearest elite one-armed competitor and twice what some other top pros generate. Ideally, the approach sends the ball flirting with the right edge of the lane before hooking sharply into the center and creating an explosion of pins. "When he hits the pocket, it's curtains," says John Jowdy, a coach since 1948. "The ball is very destructive."

Mr. Belmonte is the best-known practitioner of a style that's actually gaining converts. "We're only three or four in the world, and we're bowling so well. Imagine if there were 50 of us," he says. He occasionally competes with fellow two-hander Osku Palermaa, a Finnish pro, on the European circuit. In 2006, Ohioan Chaz Dennis became the youngest player to roll a perfect 300 game at the age of 10 using the technique, and the entire Bolivian national team adopted it last year. Even Walter Ray Williams Jr., the most decorated bowler in the Professional Bowlers Association in his 26th year on the tour, has started dabbling in it in competition.