TYSON GAY tumbled to the ground at the start of his 200-metre quarter-final heat at the United States Olympic athletics trials yesterday and had to be carted off the track.

Running in the seventh lane, Gay was speeding to the lead in the first turn, but on his 14th stride, something went wrong. He went airborne, fell, then laid on the ground in pain, grabbing his left thigh and grimacing.

Gay already had qualified for the Olympics in the 100m, but his availability for the Games now will be determined by the severity of his injury.

Though he's the defending world champion in the 200, trials rules call for the top three finishers to make the Olympic team - no exceptions.

This was a stunning setback for the 25-year-old sprinter, who last week set the American record in the 100 at 9.77 seconds. In the final, he ran it in 9.68, the fastest time recorded, but not a world record because the tailwind was too strong.