MELBOURNE, March 28 (Xinhua) -- Michael Phelps and Laure Manaudou both claimed sensational wins here on Wednesday by breaking world records at the World Championships.

One day after breaking Ian Thorpe's six-year-old world record in the men's 200 meters freestyle, Phelps showed his preeminence again in his pet event, the 200 meters butterfly.

The wunderkind was totally unmatched in the pool. When he geared up in the final 25 meters, the world record mark was even dropped behind in body length.

Phelps finished the race in one minute and 52.09 seconds, 3.04 seconds later, the runner up Wu Peng from China touched the wall and Russian Nikolay Skvortsov claimed the bronze in 1:55.22.

"I surprised myself, I went so fast," said the 21-year-old prodigy after clinching his third gold at the World Championships.

The gold enabled the U.S. team to lead the swimming medal table with eight golds.

French star Manaudou brought another fantastic show ten minutes later.

The fifth qualifier went under the world record pace all along in the women's 200 meters freestyle final and updated the world record in 1:55.52.

The 20-year-old had swum ten race before the final and had collected a gold from the 400 meters freestyle and a silver from the 100 meters backstroke.

"I am much better at the 400m. Today, I just performed exceptionally well - it was an exception," said Manaudou, who defended her title in the 400 meters freestyle last Monday with a new Championships record.

Italian Federica Pellegrini, who set the world record of 1:56.47 in Tuesday's semis, finished third in 1:56.97.

Annika Lurz from Germany also surpassed Pellegrini's world record in 1:55.68, but had to settle for second.

Besides, Oussama Mellouli became the first Tunisian to win a gold at a FINA World Championships by claiming victory in the 800 meters freestyle event.

The silver medallist in the 400 meters freestyle finished the last final on Wednesday in 7:46.95, 0.96 second faster than runner-up Przemyslaw Stancyk from Poland. Craig Stevens grabbed the bronze for the host in 7:48.67.

Grant Hackett, the world record holder and defending champion, suffered again for only managing a seventh finish in 7:55.39.

"It's extremely disappointing when you've swum almost 20 seconds faster than that time," said Hackett, who also failed to defend his title in the 400 meters freestyle last Sunday.

The world record of women's 50 meters backstroke fell in the semis while American Leila Vaziri qualified the final first in 28.16 seconds.

The other gold on Wednesday was pulled off by Oleg Lisogor from Ukraine. The world record holder finished first in the men's 50 meters breaststroke final in 27.66 seconds, edging American Brendan Hansen by a margin of 0.03 second.

Cameron Van Der Burgh from South Africa took the third place in27.88 seconds.

Phelps is going to display his sharp form again on Thursday, as the eight times Olympic medallist is slated to swim the 200 individual medley final.

The flying Dutchman Pieter Van Den Hoogenband will fight for his first world champion title in the men's 100 meters freestyle race where the defending champion Filippo Magnini from Italy and the top qualifier Jason Lezak from the United States are aggressive to hold up the Olympic champion.