KEY POINTS:
American Ryan Lochte set a world record of 1m 54.32s in the men's 200m backstroke final at the world championships last night.
Lochte sliced 0.12s off the previous record of 1m 54.44s set by compatriot Aaron Peirsol at last year's Pan Pacific championships in Canada.
Lochte's success ended Peirsol's seven-year winning streak.
Peirsol, the world and Olympic champion, was under his world-record pace through 150m. He and Lochte went stroke-for-stroke over the last 50m, with Lochte touching first.
Austria's Markus Rogan was third.
Peirsol hadn't lost a 200m backstroke race since the 2000 Sydney Olympics, when he finished second to American Lenny Krayzelberg.
Lochte won his first race in Melbourne, having got silvers in the 100m backstroke behind Peirsol and the 200m individual medley behind another American, Michael Phelps.
It was the meet's 11th world record.
Australian Libby Lenton won the women's 100m freestyle final to collect her third gold medal.
Lenton, 22, won the sprint in 53.40s, equalling the second fastest time in history, just 0.10s outside Britta Steffen's world record of 53.30s.
Marleen Veldhuis, of the Netherlands, finished second in 53.70s after leading the field at the turn under world record pace and Steffen was third in 53.74s.
Lenton, who held the previous world record at 53.42s before Steffen broke it at last year's European championships, won gold in the Australian 4x100m freestyle relay on Sunday and a second in the 100m butterfly.
Commonwealth Games 200m butterfly champion Moss Burmester, was 19th fastest from the heats and missed qualifying for the semifinals in the 100m butterfly.
Earlier breaststroke specialist Zoe Baker was 29th fastest in the 50m butterfly heats ahead of Liz Coster while Cameron Gibson and Mark Herring missed going through in the 50m freestyle.
Both lifted their world rankings considerably to 37th and 39th respectively from the 198 entries in the splash and dash.
The Kiwi quartet of Burmester, Andrew McMillan, Robert Voss and Michael Jack produced a big improvement for 16th fastest time in the 4x200m freestyle relay.
They clocked 7m 22.18s, nearly seven seconds better than their qualifying time.
But late last night Corney Swanepoel (100m butterfly), Hannah McLean and Melissa Ingram (both 200m backstroke) all missed out in their semifinals.
- Reuters, AAP, NZPA
