Michael Phelps set the Susie O'Neill pool alight in Melbourne on Wednesday night with one of the most brilliant swims in recent memory -- tearing up his own world record in the 200-metres butterfly.

Phelps confirmed his status as an all-time great with his third gold of the World Swimming Championships and a performance of such absolute dominance that he finished more than three seconds ahead of fellow medallists Peng Wu of China and Russia's Nikolay Skvotsov.

The world record always looked under threat. More than half a second ahead of the world mark at the first turn, Phelps stretched the gap to 1.62 seconds at the half-way mark, the American powering home in the final 100 metres to better the old official mark by 1.71 and hit the wall in a time of 1:52.09.

Federica Pellegrini's 200-metres world record failed to last even 24 hours with Frenchwoman Loure Manaudou setting a new benchmark of 1:55.52 in the final. Manaudou showed few signs of fatigue after a heavy programme, fighting a thrilling battle for the lead with Germany's Annika Lurz. For the second night in a row, Lurz finished second in a time that was under the world record. Former record holder Pellegrini, in lane four, was never in the hunt but finished strongly to win the bronze medal.

The third world record of the night came in the semi-final of the women's 50-metres backstroke, American Leila Vaziri improving on her championship record in the heats to finish in 28.16 seconds. After her disappointing performance in the 100-metres backstroke early in the meet, Vaziri will go into tomorrow's final as favourite.

In the only 50-metres final of the night, Ukraine's Oleg Lisodor regained the breaststroke title he won in 2001. In a tight race that saw only 0.61 of a second separate the entire field, Lisodor claimed the gold ahead of American Brendan Hansen and early leader Cameron van der Burgh from South Africa.