SYDNEY, Australia (AP) -- The biggest hit at the Sydney Paralympics? Could be wheelchair rugby, a rough-and-tumble sport originally known as ``murder ball.'' A human-powered version of demolition derby, wheelchair rugby is the only contact sport in the Paralympics and makes its full-medal debut Wednesday. Reggie Richner, of San Leandro, Calif., the coach of the top-ranked U.S. team, said he expects it will pull a big crowd in Australia, home of the world champions of able-bodied rugby and a land where collisions on the field of play are worshipped. Duncan Campbell, a quadriplegic, devised wheelchair rugby in the 1970s while messing around with three friends in a gym in Winnipeg, Manitoba. He said it was a fluke that the game has taken off. ``There was no team sports for (quadriplegics) so we used to lift some weights, but we got bored with that,'' he said. ``We were in the gym one afternoon and started to throw things around -- that's where it started. ``There were no rules really ... we called it murder ball. But when people got together to define the regulations, we decided murder ball might not be the best name for a developing game.'' Wheelchair rugby is the fastest-growing international wheelchair sport, with more than 22 nations competing regularly and others showing interest. Eight teams qualified for the Paralympics, with the United States going in as the favorite after winning every major international tournament to date. Campbell, who now lives in Vancouver and works as a rehabilitation officer, is on the coaching staff of the Canadian team and says his squad is a serious gold-medal contender. ew Zealand, runner-up at the 1998 World Championship, is ranked No. 2 in Sydney, while Australia is expected to challenge for a medal.