Eamon Sullivan reclaimed his title as the fastest man in the water by breaking the 50 metres freestyle world record at the Australian Olympic trials.

The 22-year-old swimmer from Western Australia stormed down Sydney's Olympic pool to win his semi-final in 21.41 seconds, wiping 0.09 off the previous mark set by Alain Bernard of France at the European championships last weekend.

Sullivan broke Alex Popov's long-standing world record last month only to lose the record to Bernard just four days ago.

Sullivan came agonisingly close to breaking the Frenchman's 100 record on Wednesday, missing it by just two-hundredths of a second, but made no mistake with the one-lap sprint.

"It's sort of sweet to get this back after missing it last night," Sullivan said afterwards.

Sullivan's record was the fifth in six days at the Australian trials.

His teenage girlfriend Stephanie Rice broke the 200 and 400 individual medley records while Sophie Edington and Emily Seebohm took turns in breaking the 50 backstroke record.

Reuters