Michael Phelps didn't disappoint.
In his first day racing in the World Championships, the 18-year-old American bettered his own world record in the 200m butterfly semifinal. He lopped 0.65 seconds off the mark -- equivalent to nearly a body length in the pool.
A threat to match Mark Spitz's seven golds next year in the Athens Olympics, Phelps' performance on Tuesday even upstaged Ian Thorpe, despite the "Thorpedo" winning gold to defend his world 200m freestyle title.
This could be just the start.
Phelps' time of 1 minute 53.93 seconds could go lower in the final. That would leave him with five more events -- and he's a threat for gold and world records every time he swims.
"I do think there is another level he can go to if he's in the right mode and things are going well," Phelps' coach Bob Bowman said. "I think he could take it to another level tomorrow [yesterday]."
Asked about coaching a prodigy, Bowman smiled: "I just try to stay out of the way and smile and make sure he has water to drink."
If the Baltimore native needed extra motivation, he got it last week when former Australian coach Don Talbot said any comparison of the upstart American to the triple Olympic champion Thorpe was "absolute nonsense."
"When he said that, that put a lot of fire" in me. "That really got me more motivated than I already was. Having that in mind is going to hopefully get me through these championships pretty well."
Phelps sensed Tuesday's record was coming after a morning heat where "I felt the best I've ever felt."
"It [the record] didn't feel as hard as the other ones felt," he said. "I'm not going to say it felt easy, but I definitely felt good out there."
Despite swimming six events, which will put him in the pool a dozen times before the worlds close on Sunday, Phelps said there's no holding back.
"I won't back off," he said. "If another record comes, another record comes."
Phelps vs. Thorpe is the personification of American swimming vs. Australian swimming.
Phelps holds the world records in the 200m individual medley (1:57.94), 400m IM (4:11.09) and the 200m butterfly. He is also just .03 behind Australian Michael Klim's 100m butterfly record of 51.81.
Thorpe holds the 200m (1:44.06), 400 (3:40.08) and 800m freestyle (7:39.16) records. Their only head-to-head comes in the 200m IM with the final set for Friday.
Thorpe is already bracing for a rare defeat as he faces Phelps and defending Olympic champion Jani Sievinen of Finland.
"I suspect that they'll probably be swimming faster than I will."
Thorpe won his 200m freestyle in 1:45.14, coming from behind to beat silver medalist Pieter van den Hoogenband (1:46.43) of the Netherlands. Van den Hoogenband, the defending Olympic champion, had been faster than Thorpe in both qualifying and the semifinals.
"It was an average time, but I'm happy with the result," said Thorpe, who won gold in the 400m freestyle on Sunday.
Thorpe's countryman Grant Hackett took bronze (1:46.85), rounding out a 1-2-3 finish among the current and the two former world record-holders in the event.
After three of eight days of swimming, the US, Australia and Germany each have three gold. Australia has nine overall, the Americans eight, and Germany five.
In Tuesday's 1,500m freestyle final, Hannah Stockbauer of Germany won gold with the second fastest time (16:00.18) in history. She finished several lengths ahead of silver medalist Hayley Peirsol (16:09.64) of the US and bronze medalist Jana Henke of Germany (16:10.13).