The Jamaican stepped down from the final Olympic warm-up. He insists he will be fit to run at London 2012.
After losing twice to training partner Yohan Blake at the weekend, Usain Bolt's chances of defending his Olympic 100 and 200 metres crowns appear to have receded further after his coach, Glen Mills, admitted yesterday that the sprinter had suffered an injury setback.
Mills, who also coaches Blake at the Racers Track Club in Kingston, described it as a "slight problem" without elaborating further, though it was sufficiently serious for him to pull Bolt out of the Diamond League meeting in Monaco in two weeks' time, where he had been due to contest the 200 metres in his final race before the London Olympics.
Bolt's withdrawal means his next race will be in the first-round heats of the 100 metres in the Olympic Stadium on August 4.
In a statement, Mills said: "After careful assessment, I have had to withdraw him from the Samsung Diamond League Meeting in Monaco on July 20 to give him sufficient time for treatment and time to train and prepare for the Olympic Games in London."
In the same statement, Bolt insisted that he would be on the start-line in London but did not provide any details about the nature of his latest setback.
"I am happy to have earned my spot on the Jamaican Olympic team despite the challenge," Bolt said.
"I will be in London to defend my titles in the 100, 200 and 4x100 metres.
"I want to congratulate my fellow Racers Track Club Members along with the other athletes who made the team. I thank everyone for their support."
Bolt was well below his best at the Jamaican Olympic trials in Kingston at the weekend, where he was beaten by Blake, the 100 metres world champion, in both the 100 metres and 200 metres.
It was Bolt's first defeat in a 200 metres race other than a qualifying heat since September 2007.
Immediately after the 200 metres final, a physiotherapist came onto the track to stretch out Bolt's right hamstring, though when Bolt was asked at the trials whether he was carrying an injury, he was evasive.
"We'll talk about that some other time," he said.
The latest news raises serious doubts over whether Bolt will enjoy the same dominance in London that he did in Beijing, especially now that the in-form Blake will be ready to exploit any weakness.
Justin Gatlin, the 2004 Olympic champion, and fellow American Tyson Gay will also be hoping to take advantage of Bolt's problems and they have the chance to send out a message when they take on local favourite Christophe Lemaitre at this evening's Diamond League meeting in Paris.
Gay, who booked his Olympic place when he clocked 9.86?sec to finish runner-up behind Gatlin at the United States trials, is back after an absence from competitive running for almost a year after undergoing surgery on a chronic hip injury.
"In March I didn't even know if I was going to be able to go to the trials, I was in so much pain," said Gay, who is the second fastest sprinter in history after Bolt.
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