Rome, Aug 2: Michael Phelps on Saturday broke the world record in the men's 100m butterfly to win world championship gold in the Foro Italico in Rome.
Phelps said that it was like a show-down between him and Serbian Milorad Cavic, which he managed to win in a time of 49.82 seconds.
American-born Cavic had said before the race that he was prepared to buy Phelps a polyurethane bodysuit, if his (Phelps') suit was not fast enough.
Cavic finished 0.13 seconds behind Phelps, who cheered wildly at the finish and pointed at his suit. He then ignored Cavic as he swam over to third-placed Rafael Munoz and congratulated him.
Earlier in the session Zimbabwean Kirsty Coventry, who was hoping to win at least three medals at this competition, finally picked up her first when she took the women's 200m backstroke in a world record time of 2:04.81.
She beat Russian Anastasia Zueva by .13 seconds. The bronze medal went to American Elizabeth Beisel in a time of 2:06.39.
Brazilian Cesar Cielo Filho showed why he is considered the best sprinter in the world when he added the gold in the 50m freestyle to the 100m gold that he won earlier in the competition.
Cielo Filho swam a championship record to beat France's Frederick Bousquet (21.21) and Amaury Leveaux (21.25) into second and third place.
In the women's 50m butterfly, Australian Marieke Guehrer was a surprise winner in a time of 25.48, beating Zhou Yafei by nine hundredth of a second.
Third place went to Norwegian Ingvild Snildal, who was a further hundredth behind.
Guehrer was totally shocked when she got out of the water. "Are you sure that I won, it must be a mistake. They must have made a mistake," she asked an Australian swimming official.
In the semi-finals of the women's 50m breaststroke Australian Sarah Katsoulis led the field into the final with a time of 30.33, beating Annamay Pierse by seven hundredth of a second.
Cate Campbell topped the rankings in the women's 50m freestyle ahead of Marleen Veldhuis. The Briton Campbell swam 24.08, 0.12 seconds faster than the Dutch woman.
German 100m gold medallist and world record holder Britta Steffen had the third-fastest time, while 42-year-old Dara Torres also made the final as eighth-fastest.
Still on the programme for Saturday evening are the finals of the women's 800m freestyle and 4x 100m medley and the semi-finals of the men's 50m backstroke.