OMAHA, Neb. - Michael Phelps won't be competing in the 100-meter backstroke at the US Olympic swimming trials, somewhat easing his busy schedule.

Michael Phelps celebrates his win and new world record in the Men's 400m Individual Medley at the US Olympic Swimming Trials in Omaha, Nebraska, June 29, 2008. [Agencies]

The six-time Olympic gold medalist's name was absent from the heat sheets released Sunday, leaving world record holder Aaron Peirsol without one of his biggest rivals in the event. But Peirsol will still have to face Ryan Lochte.

It's the second event Phelps has dropped at the trials. He still has six events left during the eight-day meet.

Phelps will be in action Monday, swimming in the same preliminary heat of the 200 freestyle as Lochte, who lost to Phelps in the 400 individual medley Sunday night.