Caines has endured a difficult year

Malachi Davis, the most controversial selection in the British team, also failed to qualify for the semi-finals.

But Tim Benjamin made it through to the semi-finals as a fastest loser to boost British hopes.

Caines said: "I've had a bad year. I've had knee problems all year and it hasn't gone right for me. I felt pain out there but that was bad."

Jeremy Wariner of the USA and Jamaica's Michael Blackwood looked the most impressive of qualifiers.

And Benjamin had to work hard over the last 80 metres to make sure of progressing to the next round.

He said: "Running down the back straight there was a really stiff wind, and the guy outside me went off like a bat out of hell.

"I picked up an injury in Cyprus and it took a lot to get it out of my mind. But it feels fine now and I'm pleased to have made the semi-final."

Caines was clearly disappointed despite having done well just to make it to Athens after an injury-hit season.

"I have missed a lot of training but I tried to keep my head strong, but it just didn't happen for me today."

Davis is the American who made a last-gasp entry to the GB team after learning he could acquire a British passport thanks to his English mother.

"The experience altogether has been fun but I am not too pleased with my race," he said.

"I need to take the experience and build on it but competing at the Olympics is a lifetime dream fulfilled."