Athletics-U.S. world relay hopes take a hit as Kerley out with injury

The United States' relay hopes took a hit on Wednesday as 100 metres champion Fred Kerley will not run in the 4x100 metres relay due to injury.

The Tokyo silver medallist led a U.S. sweep of the 100 metres podium on Saturday but finished sixth in the 200 metres semi-final on Tuesday after grimacing with pain down the final straight. He told reporters after the race it was "just a cramp" but his agent confirmed a day later that he had sustained a "slight injury" to his quad, leaving him unavailable for the U.S. title defence later this week.