Rome, Italy (My Sportsbook) - No photo-finish was needed this time, but American Michael Phelps set the world record in winning the 100-meter butterfly final at the World Swim Championships, edging Serbian Milorad Cavic in a rematch from the Olympics last summer.

It was in Beijing last August when Phelps narrowly edged Cavic by 1/100th of a second for the gold medal, but on Friday the Serbian set the world record with a time of 50.01 seconds during the semifinals.

One day later in the final, Phelps was fourth at the halfway turn and was a half-body length behind Cavic with nearly 25 meters left, but the record gold- medal setting American rallied and passed his Serbian counterpart before finishing in a time of 49.82 seconds. That was .13 seconds ahead of Cavic. Spain's Rafael Munoz was third.

After the race, Cavic stared in disbelief before shaking Phelps' hand.

Also Saturday, Zimbabwe's Kirsty Coventry won the women's 200-meter backstroke in a world-record time of 2:04.81. That topped her previous time of 2:05.24 at the Olympics last year when she won the gold medal. Anastasia Zueva of Russia was second, .13 seconds off the pace, while American Elizabeth Beisel was third.

Australian Marieke Guehrer captured the final in the women's 50-meter butterfly in a time of 25.48 seconds. China's Zhou Yafei was second and Norway's Ingvild Snildal came in third. American

Brazil's Cesar Cielo Filho won the men's 50-meter freestyle final in a time of 21.08 seconds, just ahead of world record-holder Frederick Bousquet of France (21.21). Frenchman Amaury Leveaux was third. Americans Cullen Jones and Nathan Adrian were fifth and sixth, respectively.

Cielo won the gold medal in the 50 free at the Beijing Olympics. It was Brazil's first gold of the 2008 games and first gold ever in swimming.

Denmark's Lotte Friis won the women's 800-meter freestyle final in a time of 8:15.92. China won the women's 400-meter medley relay in a world record time of 3:52.19.

American Dara Torres barely qualified for the final in the 50-meter freestyle as she finished eighth among the semifinalists. The 42-year-old Torres, a five-time Olympian, won the silver medal in the 50 free at the Beijing Olympics.