Wariner set an Olympic Stadium record in running the sixth-fastest 400 ever. Fellow American Michael Johnson set the world record of 43.18 in 1999.

Running in nearly perfect conditions, Wariner took the lead coming into the last curve and was unchallenged the rest of the way. He was followed by Americans Kerron Clement (44.48) and Darold Williamson (44.90).

"Very good race, this is now my personal record," said Wariner, who won the one-lap race last year in 44.02. "I ran well in Stockholm last year, now even better. I just love to run here."

Any athlete who breaks the stadium record earns a diamond valued at $10,000.

Aries Merritt also earned a diamond by winning the 110 hurdles in 13.09, leading an American sweep of the top five places. Colin Jackson of Britain held the old stadium mark of 13.12 from 1999.

"The shuttle-hurdle relay warmed me up very well — it was a good race," said Merritt, who ran the anchor leg for the winning American quartet in the 4x110 hurdles.

World-record holder Asafa Powell of Jamaica failed to improve his stadium record from last year, winning the 100 in a relatively slow 10.04. Derrick Atkins of the Bahamas was second in 10.05.

For Powell, who won last year in 9.86, it was the last race before the Aug. 25 world championships in Osaka, Japan.

"I did not feel so good today, so I did not push it as hard as I should have," Powell said.

Powell twice last year equaled his 100 world record of 9.77 set in 2005, going undefeated in the discipline with an unprecedented 12 sub-10 races. His fastest time so far this year is 9.90, second behind Tyson Gay of the U.S. (9.84).

Me'Lisa Barber led a 1-2 finish for the U.S. in the women's 100 meters with a time of 11.03 seconds. Sanya Richards, doubling in the 100 and 400 meters, was next in 11.05 for a personal record.