Tyson Gay, getting what he said was his fastest start ever, won the 100 metres in the year's fastest time, 9.84 seconds, at the US Championships on Friday.
With a blazing final 50 metres and a strong start, Gay won the race by an impressive 0.23 seconds, the largest margin of victory in a US championships 100 metres since electronic timing began in 1975.
"I was really hoping to get the world record, but the wind conditions weren't too friendly," said Gay, who ran into a headwind of 0.5 metres per second.
Only former world record holder Maurice Greene, who ran 9.82 seconds at the 2001 world championships, has run faster into a headwind. His headwind was 0.2 meters per seconds.
University student Trindon Holliday finished second in 10.07 seconds and collegiate champion Walter Dix was third in 10.09.
"That was basically my PR (personal record) so I know I am ready to run faster," added Gay, who has run times of 9.76 and 9.79 seconds with assisting winds this year.
Jamaican Asafa Powell holds the world record of 9.77 seconds which since-suspended American Justin Gatlin later equalled.
Dix, the collegiate 100 and 200 metres champion, had said earlier he would not run the final, but changed his mind and said he would now go to the world championships.
Gay will begin his quest for a 200 metres title with Saturday's qualifying.
Former world champion Torri Edwards won the women's 100 metres in 11.02 seconds into a headwind.
The 2003 titlist was joined on the U.S. world championship team by 2005 world champion Lauryn Williams (11.16), Carmelita Jeter (11.17) and world 200 metres gold medallist Allyson Felix (11.25).
The U.S. has four world championship berths in the event because defending champion Williams received a bye.
IAAF female athlete of the year Sanya Richards dominated women's 400 metres qualifying in 50.02 seconds, the fastest time in the world this year. LaShawn Merritt was the fastest man in qualifying at 44.44 seconds.
Michael Tinsley added another 2007 world leader, topping the 400 metres hurdles semi-finals in 48.02 seconds.
Olympic and world champion Dwight Phillips claimed the men's long jump with a wind-assisted 8.36 metres, and world silver medallist Brad Walker won the men's pole vault at 5.70 metres.
World champion Bryan Clay withdrew from the decathlon competition, saying he was suffering aches and pains from a recent event. The Olympic silver medallist will still be eligible to defend his world title.
The championships continue until Sunday with the top three finishers qualifying for August's world championships provided they have met the standards.