Back injury knocks Hardee out of decathlon

hopes of topping the medals table in Beijing.

The 2009 and 2011 gold medallist injured his left lower back on his final attempt in the long jump, the second event of the two-day competition. He made two attempts in the shot put but withdrew after throwing a subpar 10.20 metres.

"I'm devastated to have to withdraw," Hardee said in a statement. "I tried everything to try to make it through but it just wasn't meant to be."

Hardee had entered the competition with the year's top score, 8,725 points, and had been tabbed for a silver medal behind team mate Ashton Eaton, the world record holder.

A hamstring cramp in the high jump had ended his 2013 worlds, the first time since 2008 he had not won a medal at a major championship.

"I need to focus now on getting prepared for 2016 and what will be my final Olympic campaign," Hardee said.

After a slow start, the United States had three gold medals through Thursday, half as many as Kenya, but led the Africans in total medals by one with 12.