LONG BEACH, California (AFP) - Michael Phelps, preparing for a multiple-medal assault at the Beijing Olympics, won two events Saturday at the Southern California grand prix meeting.

The US swimming star nabbed the 100-yard and 500-yard freestyle titles at the meet, which is swum in short-course yards.

In his opening race of the evening, Phelps came from behind to beat Matt Grevers in the last 25 yards of the 100-yard free.

Phelps clocked 41.93sec. Grevers and Olympian Jason Leza third.

In the 500-yard free, Phelps took an early lead and won in 4:10.43. Erik Vendt was second and Peter Vanderkaay third.

In the women’s 200-yard backstroke, world champion Margaret Hoelzer edged Mary Descenza with Samantha Pearson third.

Descenza added to her medal count for the night with a win in the 200-yard butterfly ahead of Olympian Dana Kirk and Kim Vandenberg.

In the men’s 200-yard fly, Davis Tarwater won ahead of Mexico's Juan Veloz, with Pat Cary third.

Grevers took home his first gold medal of the meet and second medal of the night with his win in the men’s 200-yard backstroke, ahead of Peter Marshall and Britain's Simon Burnett.

Kaitlin Sandeno grabbed her second gold medal of the meet in the women’s 500-yard free, adding it to the 1,000-yard free she won on Friday. Kara Lynn Joyce won the women's 100-yard free.