Great Britain will not be able to defend their Olympic 4x100 metres relay title after being disqualified from tonight's semi-finals in Beijing.
The British quartet of Simeon Williamson, Tyrone Edgar, Marlon Devonish and Craig Pickering finished second behind Jamaica in 38.71 seconds, but botched the final changeover.
Pickering went off way too early on the final leg and only received the baton from Devonish after running outside the changeover box at the top of the home straight.
The United States, runners up to Britain in Athens four years ago, also crashed out after Darvis Patton and Tyson Gay dropped the baton on the final changeover in the opening semi-final.
A disappointed Pickering told BBC Sport: "I'm very disappointed. It's a shame because we've got a really good team. I'm sorry."
Marlon Devonish leapt to Pickering's defence. He said: "Craig should not take full responsibility, it's a team event. We trained really hard for this and anything can happen."
As for the Americans, world champion Gay - who failed to make the final of the individual 100m - said: "The stick was in my hand but when I went to grab it he had already let go. It takes a second to feel it.
"It is probably my fault. I am going to take the blame for it. I have never dropped a stick in my life. It is just the way it has been happening for me this year."
There was more misery for the United States in the women's relay when they again dropped the baton on the final changeover, Torri Edwards and Lauryn Williams this time the guilty duo.
Belgium won the first semi-final in 42.92 seconds ahead of the British quartet of 100m individual finalist Jeanette Kwakye, Montell Douglas, Emily Freeman and Emma Ania.
Jamaica cruised to victory in the second semi-final with Veronica Campbell-Brown running the anchor leg 90 minutes after successfully defending her 200 metres title.
Devonish, the only member of the victorious team from Athens, added: "We're bitterly disappointed, totally gutted.
"There's been a lot of expectation on this team. We didn't come here to play games but it's a team event and we all take full responsibility. There are no excuses.
"I'm not sure if Craig went early, everything happens so quickly in relay."
Sayers, who suffered a bout of food poisoning at the team's training camp in Macau before arriving in Beijing, said: "To be beaten by two people who have thrown 70m, I can't do any more. But fourth is a difficult place to finish.
"You could see it was going to be a big championship and I think it was one of the greatest finals ever and I feel very proud to have been part of it."
Asked about her British record throw, she added: "I don't think it was one of my better throws, I think it was just a bit drier! Conditions were dragging things down a bit."
In the men's 400m, Martyn Rooney finished sixth in the final as defending champion Jeremy Wariner was surprisingly beaten into second place by team-mate LaShawn Merritt.
Merritt took gold in a time of 43.75s with David Neville's desperate lunge at the line securing a 1-2-3 for the American trio.