Rome, Aug 2 (DPA) Michael Phelps 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.