Phelps sets new world mark

Phelps is aiming for seven golds at the Athens Olympics

American Michael Phelps broke his own 400m individual medley world record at the US Olympic swimming trials.

The 19-year-old triple world record-holder clocked 4:08.41 to lower the 4:09.09 mark he set at last year's World Championships in Barcelona.

Meanwhile, 15-year-old Katie Hoff set a US record in winning the women's 400m individual medley in a time of 4:37.67.

Klete Keller won the men's 400m freestyle in 3:44.19, breaking Phelps's American record by over two seconds.

"The 400m IM is a draining event," Phelps said.

"To be able to have that out of the way is nice. I'm ready to move on to Thursday and the 200m freestyle."

Phelps is seeking to win seven gold medals at next month's Athens Games.

Academy: Watch all our top swimming masterclasses