Great Britain's men's sprint relay team have missed out on a place in the final of the 4x100 metres following a mistake in the baton changeover at the Olympic Stadium.
The host nation were disqualified when anchor leg runner Adam Gemili set off too early as he was about to take the baton from Danny Talbot.
The 18-year-old athlete slowed down dramatically, but the changeover still occurred outside the designated area. Gemili sprinted for the line and came home second, but realised their mistake, putting his hands on his head in despair.
Jamaica, without Usain Bolt, qualified safely, but the United States were the quickest through in a new national record of 37.38 seconds.
Meanwhile, Team GB's women's 4x400 metres relay team booked their place in Saturday's final by finishing a comfortable third in their heat. The quartet of Shana Cox, Lee McConnell, Eilidh Child and Christine Ohuruogu, the individual silver medallist, clocked three minutes 25.05 seconds.
The British athletes, who are the reigning world indoor champions, finished behind heat winners the United States and Russia.
Jo Pavey and Julia Bleasdale finished seventh and eighth respectively in the women's 5,000 metres final at the Olympic Stadium. Ethiopia's Meseret Defar claimed gold as she denied her compatriot Tirunesh Dibaba the chance to add another title to the 10,000m crown she won a week ago, having taken gold in both athletics events in Beijing.
Sophie Hitchon finished 12th in the hammer final at the Olympic Stadium following an impressive qualifying throw. The 21-year-old athlete, who broke her British record with a 71.98m throw in qualifying, could only manage a best of 69.33m on Friday.
Great Britain finished an agonising fourth in the 4x400 metres final as a courageous anchor-leg run from Martyn Rooney just came up short. Rooney attacked round the final bend and on the home straight past Russian athlete Pavel Trenikhin and was closing on Trinidad's Deon Lendore, but was held off.
The host quartet, which also included Conrad Williams, Jack Green and Dai Greene, finished in two minutes 59.53 seconds. Bahamas won in 2mins 56.72secs, with the United States second and Trinidad third, 0.31s ahead of Britain.