Christine Ohuruogu's bid for a third world title ended in disappointment as she came home last in the 400 metres final in Beijing.

The defending champion had nothing left in the home straight where she is usually so strong as she crossed the line in 50.63 seconds.

She collapsed to the track at the finish, head in hands, clearly devastated.

Ohuruogu had the effortless Allyson Felix one lane inside her and the American went off like a train. The Briton tried to respond and was possibly made to pay for that effort, as she faded Felix charging down the home straight to take gold in a world-leading 49.26 seconds.