U.S. swimmer Michael Phelps Sunday defended his Olympic title in the men's 400 meters individual medley with a new world record.

Phelps stormed to touch the wall first with a time of four minutes 3.84 seconds, shaving 1.41 seconds off his own world record set at the Olympic swimming trials in July.

Hungarian Laszlo Cseh won silver in 4:06.16. Phelps's teammate, Ryan Lochte, who is seen as a consistent silver medalist in his competition against Phelps, was edged to the third place.

"It's a tough race the whole way through. That's a pretty emotional race," Phelps said after the race. "It wasn't comfortable in a close race the first 200 meters, but my breaststroke is stronger."

Phelps, known as the "Baltimore Bullet", is expected to break Mark Spitz's record of seven golds at a single Summer Games. At the 2007 World Championships in Melbourne, he became the only swimmer to set five world records at one international event.

U.S. President George W. Bush was present at the Water Cube, cheering up for the American swimmers.

Donning a sky blue blouse, Bush watched intently at the race. He stood up in cheers when Phelps started his charge with the freestyle, waving an American national flag.

Bush's coming obviously cheered Phelps up. "To have president coming watch is pretty cool. I looked up and saw him waved the flag. That's pretty cool to have the president say congratulations," Phelps said.