Michael Phelps earned his fifth gold medal as the U.S. relay team won the 400-meter medley in world record time.
Phlelps, 24, helped his team pull away from Germany and Australia in the butterfly leg -- winning in 3 minutes, 27.28 seconds and shattering the 3:29.34 mark set by the U.S. at the Olympics last summer.
"I think a competition like this that really brings out the best in me," Phelps told The New York Times. "It doesn't matter how much energy I have, it's all going to go into every race. I think that's one of the things that I enjoy most is stepping onto the blocks no matter what kind of shape I'm in and racing."
Phelps, who won a record eight medals at the Beijing Olympics last August, arrived at the world championships in Rome underprepared after taking six months off.
"I think it's not how you start, it is how you finished," Phelps said Tuesday after he lost the 200 freestyle.
Still, Phelps managed to paddle his way back to the top.
New suits made of polyurethane have been credited with the number of records shattered at the championships but the special suits are slated to be banned in January .
U.S. & World
Phelps, wearing a supposedly inferior suit, beat rival Milorad Cavic again on Saturday in a rematch of the infamous Beijing Olympic race in which Phelps won by one-hundredth of a second. Cavic has maintained that he hit the wall first.
The Serbian offered to get Phelps an X-Glide polyurethane suit "within the hour" or buy him one so he couldn't make any more excuses.
"How can it not motivate you? When there are things that are said, the only thing it does for me is fire me up," Phelps told NBC. "It does nothing but literally motivate me to no end, and I love it."
