Phillips Idowu has pulled out of the triple jump at the London Diamond League meeting with a hip problem.
The 33-year-old, who is considered one of Team GB's best gold medal prospects at London 2012, has competed just three times this year.
He had been expected to face the USA's world champion Christian Taylor.
Idowu apologised for his absence on Twitter: "Sorry to have to pull out, slight bit of muscle tightness. I will be fine in a day or two."
In the build-up to the event at Crystal Palace, Idowu denied stories he injured his foot at a previous Diamond League meeting on 1 June.
His last appearance came in Eugene, Oregon where he struggled to hit top form - registering leaps of 16.43m and 17.05m, well short of his personal best of 17.81m. He fouled in the third round and took no further part in the competition.
Idowu told BBC Sport he withdrew in Oregon as a precaution because of wet conditions.
"I've not commented on it and have kept my head down and focused on working and preparing for the Games," Idowu said.
"I understand why it was assumed [I was injured] because I withdrew from the competition in Eugene in the third round.
"But I withdrew from that competition because it was raining, it was wet and cold and I slipped on the board in my third attempt and I didn't want to risk my chances for the Games by trying to win that competition and picking up any injury to myself."
Idowu, who won a silver medal at Beijing in 2008 and again in the 2011 World Championships, also said that his preparations for London 2012, which also included missing the Olympics trials, have been helped by his lack of action.
"This year I've been able to focus on training," he said. "For the last 30 days I've worked really, really hard.
"I'm pleased with the work I've done and impressed with how hard I've worked. I'm happy and optimistic."