Great Britain's established sprinters leapt to the defence of 18-year-old Adam Gemili on a night of yet more relay woe for the hosts at the Olympic Stadium.

While the men's 4x400 metres hurdles team finished an agonising fourth in the final event of the night, a courageous anchor-leg run from Martyn Rooney coming up just short, an all-too-familiar fumbled changeover cost the 4x100m quartet a place in the final.

Britain were disqualified when anchor leg runner Gemili set off too early as he was about to take the baton from Danny Talbot, 21. The 18-year-old slowed down dramatically, but the changeover still occurred outside the designated zone.

Gemili sprinted for the line and came home second, but the fact he immediately put his hands to his head told the story.

Chambers, 34, said: "It was a massive task for the two young boys. We had to use the best we had, those were the cards that were dealt to us and we had to deal with them as best as possible.

"They are taking responsibility for it. We are all out there trying our best. We had to put experience first and let the youth try and deliver. We asked a big task of them and they are disappointed as you can see.

"We were banking on getting ahead well enough, which we were, we were in a good position. We would have got the final and in the final we would have made changes."

Gemili said on the BBC: "It really is disappointing. I think I went on the check mark, maybe a tiny bit early."

The mistake continued a woeful record for Britain in the event, who, aside from the one glorious exception at the Athens 2004 Olympics, have lurched from one failure to the next.

Dropped batons at the Olympics in Atlanta (1996) and Sydney (2000) and the World Championships in Edmonton (2001), along with a disqualification at the last Olympics in Beijing and the World Championships in Daegu (2011) have ended their chances.

They also went out in the first round at the last European Championships in Barcelona two years ago, while at the most recent Europeans in Helsinki earlier this summer they also failed to get the baton round.

Malcolm said: "We know we're going to get the snipers on us now for not getting the baton round but you have to take the positives from this.

"We have two exceptional youngsters on the team who did an exceptional job today, it was just unfortunate.

"Adam didn't go off early, he went off on the check mark, but whatever you do in training you can't mimic when you get in that arena.

"When you have someone who is exceptionally talented they rise to the occasion and that's what Adam did. He rose to the occasion, got his adrenalin going and went out hard. It was unfortunate Danny couldn't catch him.

"You can't blame a lack of experience. To come in here in the biggest race of his life and be asked to run the last leg is a big burden, but he is the best guy to do the job right now."