Great Britain finished an agonising fourth in the 4x400 metres final at the Olympic Stadium 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.
South Africa, with Oscar Pistorius on the fourth leg, finished eighth.