SHANGHAI - Olympic champion Park Tae-hwan won the first gold in the opening night at the world championships in Shanghai.

The Korean swimmer took gold in the men’s 400m free in 3:42.04 ahead of local favourite Sun Yang and defending champion Paul Biedermann.

Federica Pellegrini of Italy easily defended her title in women’s 400 free. She touched the wall in 4:01.97 ahead of double Olympic champion Rebecca Adlington.

Earlier in the women’s 100m butterfly semifinal, US swimmer Dana Vollmer win with 56.47s, the new world best time for 2011 and a new American record.

Following are the leading results on Sunday.

WOMEN

400 FREESTYLE
1. Pellegrini Federica ITA 4:01.97
2. Adlington Rebecca GBR 4:04.01
3. Muffat Camille FRA 4:04.06

4x100 FREE RELAY
1. Netherlands NED 3:33.96
2. United States USA 3:34.47
3. Germany GER 3:36.05

MEN

400 FREESTYLE
1. Park Tae-hwan KOR 3:42.04
2. Sun Yang CHN 3:43.24
3. Biedermann Paul GER 3:44.14

4x100 FREE RELAY
1. Australia AUS 3:11.00
2. France FRA 3:11:14
3. United States USA 3:11:96