Olympic champion Maurice Greene clocked a wind-assisted 9.78 seconds for the 100 metres, equal to the world record, at a meeting in Stanford, California.
Greene, 29, who has been increasingly troubled by injuries since winning the 100 metres at the 2000 Sydney Games, led from the start with a following wind of 3.7 metres a second.
The time equals fellow-American Tim Montgomery's world mark, set in Paris two years ago when the wind was right on the allowable limit of two metres a second.
Greene said he could have run faster without the wind.
"It makes me skip a couple of steps," he said. "I think these races are showing that I am in great form and when I get a race with no wind at my back then you will see what really happens.
"I am going to push the limits of my body and run faster than any man has run before. I still say I am the greatest of all time."
At the same meeting, Olympic women's pole vault champion Stacy Dragila equalled her season's best of 4.70 metres before making three unsuccessful attempts to break Russian Yelena Isinbayeva's world record of 4.82.
Ethiopian Kenenisa Bekele, who broke compatriot Haile Gebrselassie's world 5,000 record by two seconds in the Dutch town of Hengelo on Monday, said he planned to run the 10,000 at the Athens Olympics in August.
"Although I feel comfortable at both 5,000 and 10,000 I will run the 10,000 in Athens," Bekele said.
The three-times world cross country champion over both the long and short course distances beat Olympic champion Gebrselassie in the 10,000 final at last year's Paris World championships.
Gebrselassie, who won the 1996 and 2000 Olympic 10,000 titles, was beaten into second place in Hengelo by another Ethiopian, the world bronze medallist Sileshi Sihine. He plans to defend his title in Athens.
Mozambiques's Olympic champion Maria Mutola set a season's best of one minute 58.49 seconds in the 800 at the Hengelo meeting.
On Wednesday, Ethiopia's women's 10,000 metres champion Berhane Adere will attempt the world 5,000 record at an international meeting in Milan.
Adere narrowly failed to break Chinese Jiang Bo's mark of 14:28.09, set seven years ago, when she clocked 14:29.32 at last year's Bislett Games golden league meeting in Oslo.
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