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MELBOURNE, Australia -- Michael Phelps broke a second world record in 24 hours to collect his third gold medal at the world swimming championships on Wednesday.
The American won the 200 meters butterfly final in one minute 52.09 seconds to wipe a massive 1.62 off the previous record of 1:53.71 which he set in Columbia, Missouri last month.
China's Wu Peng finished second, nearly three body lengths behind Phelps, in 1:55.13 and Russian Nikolay Skvortsov was third in 1:55.22.
Phelps, 21, is chasing an unprecedented eight world titles in Melbourne and has won the first of his three events.
He collected his first gold medal in the 4x100 freestyle relay on Sunday and added a second when he broke Ian Thorpe's 200 freestyle world record on Tuesday.
"I surprised myself, I went so fast," said Phelps. "I wanted to go 52.00 but I didn't expect to swim 52.00.
"I'm showing I'm in solid shape now. I had a really good swim earlier in the season where I broke the world record. I wanted to take it out tonight, so I'm pretty happy."
Leila Vaziri of the United States set a world record of 28.16 seconds in the women's 50 meters backstroke semifinals.
Vaziri wiped 0.03 off the previous record of 28.19 set by Janine Pietsch of Germany at Berlin in 2005.
The 21-year-old New Yorker burst off the blocks and emerged from the water with a slender lead before going on to achieve the new mark.
"Going in to tonight I definitely had it in my mind to go that time," said Vaziri, who is competing in her first major international competition.
Laure Manaudou of France smashed the world best in winning the women's 200 meters freestyle final.
Manaudou fought off a storming finish from Germany's Annika Lurz to reach the wall first in one minute 55.52 seconds, slashing 0.95 off the previous record of 1:56.47 set by Italian Federica Pellegrini in Tuesday's semifinals.
Lurz also went under the world record to take the silver medal in 1:55.68 and Pellegrini finished third in 1:56.97.
Manaudou won the 400 freestyle final on the first night of competition and finished second behind American Natalie Coughlin in Tuesday's 100 backstroke final.
The 20-year-old Frenchwoman had entered nine events for the championships but withdrew from the 200 individual medley and the 50 backstroke to save her energy for her best events.
Oussama Mellouli became Tunisia's first world champion when he pulled off a surprise win in the men's 800 meters freestyle final.
The 23-year-old Mellouli stormed home over the last 100 meters to snatch the gold medal in seven minutes 46.95 seconds after taking silver in the 400 on Sunday.
Poland's Przemyslaw Stanczyk collected the silver medal this time in 7:47.91, after briefly taking the lead at the 600 mark, while the bronze went to Australia's Craig Stevens in 7:48.67.
Australia's Grant Hackett, twice world champion and world record holder, finished seventh in his first major meeting since undergoing shoulder surgery more than a year ago.
Phelps is chasing an unprecedented eight world titles in Melbourne.