Phelps, of Rodgers Forge, set a world record in his first event of the U.S. Olympic swimming trials, touching just ahead of Ryan Lochte to win the 400-meter individual medley in 4 minutes, 5.25 seconds last night.
After saying he had no fear of Phelps, Lochte proved it by also going under the previous record. But his time of 4:06.08 was good enough for only second with Phelps in the next lane over.
"He looked great, and what an epic swim," said Phelps' coach, Bob Bowman.
"One of the best swims I've ever seen."
Robert Margalis finished third, more than seven seconds behind the top two.
"That's absolutely incredible," Margalis said. "I'm a swimming fan as much as I am a swimmer. I'm happy for those guys.
It was a fun thing to be a part of."
Phelps won six gold medals and two bronzes at the Athens Olympics, just missing Spitz's record of seven wins at the 1972 Munich Games. Phelps - who turns 23 today - is determined to knock off the mark in Beijing.
Earlier, Lochte out-swam Phelps, even if it was only the preliminaries of the 400-meter individual medley.
Lochte was the fastest qualifier in 4 minutes, 13.38 seconds - fourth best in the world this year.
"Not bad," he said. "I felt really good and smooth the whole way. It was a good first swim of the meet."
Swimming in the last heat, Phelps touched in 4:13.43 to be second quickest.
"I'm not really too happy," he said. "That was slower than I went in worlds in the morning. Hopefully I'll be faster tonight."
Katie Hoff took the lead on the breaststroke leg of the women's 400 IM and cruised to the fastest time of 4:34.59, bettering her trials record from four years ago.
Elizabeth Beisel, a 15-year-old from Saunderstown, R.I., flirted with the world record one heat earlier before qualifying second in 4:35.76. Two-time Olympian Kaitlin Sandeno, silver medalist at the Athens Games, finished 10th - 9.22 seconds off her best time - and didn't advance to the eight-woman evening final.
Lochte is entered in a whopping 11 events and Phelps in nine, but the six-time Olympic gold medalist has already dropped the 400 freestyle.
Also advancing to the eight-man evening final in the temporary pool at the Qwest Center was Alex Vanderkaay, one of four brothers from the same family competing at the trials.