The United States may not have dominated Friday night's finals in the FINA World Championships in Melbourne but, through Ryan Lochte and their men's 4 x 200-metres freestyle relay team, they still managed to break two world records.

The Americans continued their dominance of the men's competition with another stunning relay performance, Michael Phelps, Lochte, Klete Keller and Peter Vanderkaay smashed Australia's old world mark in the 4 x 200-metres relay by over a second in a time 7:03.24.

Phelps, the star of the meet, got the Americans off the perfect start, his first leg of 1:45.36 was more than two seconds faster than any of his opponents and from there the American's claim to the gold was never challenged. So convincing was the American win that they finished nearly seven seconds ahead of second placed Australia and 7.46 seconds ahead of Canada in third place.

For Phelps it was the fourth consecutive night that he has broken and individual or relay world record and his fifth gold medal so far for the meet, while for Lochte it was his second world record on the night.

Lochte wiped rival and countryman Aaron Peirsol's name from the record books in the 200-metres backstroke. The final was always a race between the two with Peirsol, aiming to become only the second swimmer to win the same event at four world championships, leading the way in the first three laps. But in a fast finishing final lap, Lochte was too good for the reigning world champ, nudging out Peirsol by 0.48 of a second to win a time 1:54.32.

In one of the most anticipated events of the night, Australia's Libby Lenton continued her impressive championship by taking the gold in the women's 100-metres freestyle. In a star-studded final Dutchwomen Marleen Veldhuis led the field at the halfway point but was unable to maintain her lead as Lenton pounced in the final 20-metres to win the the gold in the second fastest time in history of 53.40, with Veldhuis second and German sprint star Britta Steffen taking the bronze.