Defending champion Gay out of world 200m

Defending champion Tyson Gay of the United States has pulled out of the men's 200m at the World Athletics Championships because of a nagging groin injury.

Gay will instead focus on preparing for a possible appearance in the US 4x100m relay, the US team said in a statement.

Gay's efforts in Sunday's 100m final, when he won silver in an American record of 9.71sec behind Usain Bolt's world record of 9.58, took enough of a toll on Gay that he decided "resting would better serve the interests of Team USA and himself", it said.

"Rather than risk further injury, I've decided that I will not compete in tomorrow's (Tuesday) first round of the 200m," Gay said on Monday.

"I would like to be a part of Team USA's 4x100m and believe this decision will give me the best chance to be ready for the relay. I want to help our relay as best I can."

The US team will name its first-round relay line-up after the men's 200m final on Thursday. The first round of the relay is on Friday, with the final on Saturday.