Connor Fields of the United States won his third straight BMX Supercross event when he held off Australia's Sam Willoughby by two-thousandths of a second on Saturday.
The photo finish was the closest in Supercross history.
Fields added to victories in the season-opening event in Chula Vista, Calif., and last year's finale in Chula Vista, establishing himself as one of the favorites for the London Olympics.
Carolina Buchanan of Australia won the women's race, holding off Magalie Pottier of France at the finish line. American rider Alise Post finished third and teammate Arielle Martin was fifth.