A duel between American Matt Biondi and West Germany's Michael Gross, plus the Olympic debut of triple world record holder Janet Evans highlight Sunday's start of swim competition at the Seoul Games.

Biondi's chance to match the seven gold medals won by Mark Spitz at the 1972 Olympics will receive one of its toughest challenges when the 22-year-old from Moraga, Calif., battles world-record holder Gross in the 200-meter freestyle.Competition begins with preliminary heats in the men's 100 breaststroke and 200 freestyle, plus the women's 100 freestyle and 400 individual medley. Finals in those events are set for Monday.

Gross, whose lanky 6-foot-7 frame earned him the nickname "Albatross," set the world record of 1:47.44 in the 200 freestyle to win the 1984 Olympic gold medal. He owns the best time in the world this year, a 1:47.61 swim in February. Biondi set an American record of 1:47.72 in the event at the U.S. Olympic trials last month in a preliminary heat, but lost to Troy Dalbey in the final.

To match the 1972 gold-medal total by Spitz, Biondi must win the 50-, 100- and 200-meter freestyles, the 100 butterfly and help propel three American relay teams to victory. Biondi considers the task an impossible one because the level of international competition has increased since Spitz competed.

"I'm convinced it will never happen again," said Biondi, who rates his chances of taking seven medals as slim.

Biondi owns the world record in the 100 freestyle and has the fastest time in the world this year in the 100 butterfly. But he must overcome Gross in the 200, then outsprint U.S. rival Tom Jager in the first Olympic 50-meter competition. Jager defeated Biondi at the U.S. trials and his fastest time this year, 22.23 seconds, is almost two-tenths of a second better than Biondi's best. That difference can be an eternity in a race where competitors breathe only once in their swim across the pool.

Evans, 17, from Placentia, Calif., holds world records in the 400-, 800- and 1,500-meter freestyle events, the longest of which is not an Olympic event. Her American record time of 4:38.58 in the 400 individual medley to win the U.S. trials last month is almost four seconds better than this year's second-best clocking, turned in by U.S. teammate Erica Hansen.

Kristin Otto, the top sprinter on East Germany's powerful swim squad, is favored in the women's 100 freestyle. Otto set the world record of 55.30 seconds in 1986. Great Britain's Adrian Moorhouse holds the fastest men's 100 breaststroke time this year, a 1:01.78 effort last March.