Double world champion Lenny Krayzelburg broke the Olympic men's 200-metres backstroke record this morning as he opened his bid for a second Sydney Games title.

The Ukrainian-born American, who won the 100 metres backstroke crown in Olympic record time on Monday, clocked one minute 58.40 seconds to beat the 1:58.47 set by Spain's Martin Lopez-Zubero in winning the title at the 1992 Barcelona Games.

Krayzelburg set world records in the 50, 100 and 200 metres backstroke the last time he swam in the International Aquatic Centre at Homebush Bay at the 1999 Pan Pacific championships.

"I just wanted to swim a good race. I didn't even know the (Olympic) record," he said. "I felt great in the last few days. I felt good in the warm-up. That's where I wanted to be."