EUGENE, Ore. (AP) -- Tyson Gay tumbled to the ground at the start of his 200-meter quarterfinal heat at the U.S. Olympic track and field trials and had to be carted off the track.

Running in Lane 7, Gay was speeding to the lead in the first turn, but on his 14^th stride, something went wrong. He went airborne, fell, and then lay on the ground in pain, grabbing his left thigh and hamstring.

USA Track and Field officials say Gay pulled up with a severe cramp in his hamstring.

Gay’s manager says the sprinter is at his hotel, resting and working with his physical therapist. Gay is also scheduled for an MRI as a precaution.

Gay already had qualified for the Olympics in the 100 meters, 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.

(Copyright 2008 by the Associated Press.  All Rights Reserved.)