Michael Phelps claimed the 100-meter backstroke title at the Austin Grand Prix on Saturday.

The American swimming icon also finished first in the 100m butterfly on Friday.

Phelps triumphed in 54.14 seconds, more than a second slower than his personal best. The 14-time Olympic gold medallist said his winning time showed he has plenty of work to do.

"It wasn't too bad," said Phelps, who won eight gold medals at the Beijing Olympics. "I would really like to work on being able to finish a race better. My legs were in a lot of pain. That's just lack of being in shape. I would like to feel a lot less (fatigue) than what I am, just because it's close to the world championships and we're heading into an Olympic trial year."