INDIANAPOLIS – Aaron Peirsol lowered his own world record in the 200-meter backstroke at the Short Course World Championships on Monday night and then was part of the U.S. team that set a world record in the 400 medley relay by more than 5 seconds.

In the relay, Peirsol, Brendan Hansen, Portland native Ian Crocker, and Jason Lezak finished in 3:24.09, bettering the mark of 3:25.38 set by the University of Texas in March in East Meadow.

The Americans led all the way. Peirsol led off and Hansen put them under world-record pace on the breaststroke leg. They fell slightly off record pace during Crocker’s fly before Lezak brought it home in record time on the freestyle anchor leg.

Australia was second in 3:29.72 and Russia was third in 3:32.11.

Peirsol’s time of 1 minute, 50.52 seconds in the 200 back bettered his mark of 1:50.64 set in March at a short course World Cup meet in East Meadow, N.Y. He also won the 100 back during the 25-meter competition.

Matthew Welsh of Australia was second in 1:52.54 and Arkady Vyatchanin of Russia was third in 1:54.20.

Peirsol, of Irvine, Calif., swept the backstroke events at the Athens Olympics. He also won the 200 back at the 2002 short course championships.