Tirunesh Dibaba wins first gold medal of the London Olympics . She successfully defends her 10,000 m crown . Robert Wagner retains his men 's shot put crown for Poland . Home hope Jessica Ennis leads women 's heptathlon after first day .
Tirunesh Dibaba wins first track gold of the London Olympics . Dibaba successfully defends her 10,000m crown . Tomasz Majewski retains his men 's shot put crown for Poland . Home hope Jessica Ennis leads women 's heptathlon after first day .