One day after Maryland's Michael Phelps broke a world record in the 400-meter individual medley at the U.S. Olympic swimming trials, a more subdued Phelps won the semifinal of the 200-meter freestyle Thursday evening in a time that he said disappointed him.

Phelps, 19, of Baltimore County, finished in 1 minute 47.42 seconds, beating Phoenix native Klete Keller, 22, by about two-tenths of a second.

"I didn't feel as good as I wanted to feel," Phelps said. "I guess I got a pretty decent swim in. I'm not real happy with the time, but we have another one [Friday] so I'm going to put this behind me and take a step forward tomorrow."

Phelps, who made the U.S. Olympic team with his world-record swim Wednesday, is embarked on a quest to win seven gold medals at the 2004 Olympic Games in Athens next month. Doing so would match the mark set by Mark Spitz at the 1972 Games in Munich, and would earn Phelps a $1 million bonus being offered by the Speedo swimwear company, Phelps's chief sponsor.

Phelps had placed second Thursday morning in the preliminaries of the 200 freestyle, with a time of 1:48.40. Keller's 1:48.15 was the morning's best.

Keller had set an American record Wednesday in the final of the 400-meter freestyle, reclaiming the mark from Phelps, who had seized it from Keller last August.

Phelps holds the 200-meter freestyle American record of 1:45.99. He broke the American record twice in 16 days last summer.

The world record of 1:44.06 is firmly in the hands of Australia's Ian Thorpe. Thorpe's teammate, Grant Hackett, also is strong in the event.

Eddie Reese, the coach of the U.S. Olympic men's team, said the 200 freestyle will be tough for the Americans in Athens next month.

"You've got to get by the Australian duo . . . of Hackett and Thorpe," he said. Thorpe's world record is "an amazing time," he said. "What you do is you hope he's a little off in that event."

Asked if Phelps would swim the event in Athens, Reese said: "I really think so. I hope so. It'll be a race. Michael knew what he was getting into. He'll be fine."

The final in the event is scheduled for Friday evening. If all goes as planned, it will be Phelps's second of three races that day, and his first of two that evening.