Dave Wharton twice broke his U.S. record in the men's 400-meter individual medley yesterday at the U.S. National Long Course Swimming Championships in Fresno, Calif.

Wharton was clocked in 4 minutes 17.81 seconds in the final, four one-hundredths of a second off the world record set by Canada's Alex Baumann at the 1984 Summer Olympics.

In his preliminary, Wharton finished in 4:18.45, bettering the U.S. mark of 4:18.77 he set last year.

"It just felt smooth all the way through," said Wharton, 18, of Warminster, Pa., following his record-breaking performance in the preliminary. "I thought I was on pace {for the record} after the backstroke {the second leg}."

It was the fifth record at the meet. Janet Evans set a world mark in the women's 800-meter freestyle with a time of 8:22.44. U.S. marks included Amy Shaw's 2:29.78 in the women's 200-meter breaststroke, Steve Bentley's 2:15.30 in the men's 200 breaststroke and Sean Killion's 7:52.49 in the 800 freestyle.

Evans, a 15-year-old high school junior from Placentia, Calif., won her second title last night, taking the 400 individual medley in 4:41.74.

A surprising result was the victory by UCLA's Craig Oppel in the men's 200-meter freestyle, in which Matt Biondi -- U.S. record-holder in the event -- faded to fourth. Francie O'Leary of Tucson won the women's 200 freestyle.

Among Washington area swimmers, Kelly Davies of Ashton was second in the women's 200-meter butterfly in 2:12.45 and made the Pan Pacific team; Michelle Griglione of Fairfax was fourth in the 200 butterfly (2:12.80) and qualified for the Pan American Games; Susan O'Brien of Bethesda, fourth in the 200 backstroke at 2:15.15, and Todd Dudley of Darnestown, fifth in men's 100 freestyle at 50.72, also qualified for the Pan American Games . . .

Megan Neyer of Boca Raton, Fla., edged defending champion Kim Fugett for the gold medal in the women's one-meter springboard competition at the U.S. Diving Outdoor Championships in Bartlesville, Okla. Neyer totaled 438.84 points on 10 dives, Fugett of Cincinnati 433.89. Mary Fischbach (432.21) of the University of Michigan was third.