Athletics-Gay pulls out of London showdown with Powell

LONDON, July 23 (Reuters) - World 100 metres champion Tyson Gay has pulled out of his clash with Jamaican Asafa Powell at the London Grand Prix on Friday to avoid aggravating a hamstring injury, the American said on Wednesday.

"I hoped to run in London but with the first round of the Olympic 100 metres just three weeks away, I don't want to risk anything to set things back," Gay was quoted as saying on the IAAF website (www.iaaf.org). "I apologise to the fans."

Gay suffered a hamstring strain at the U.S. Olympic Trials where his hopes of a sprint double in Beijing ended in agony when he suffered severe cramp during the 200m quarter-finals.

He will compete in the 100 metres and 4x100 relay at next month's Games.

Gay won the 100 metres at the U.S. trials in the fastest time ever run, a wind-assisted 9.68 seconds.

(Writing by Ken Ferris; Editing by Ed Osmond)