Great Britain has lost its bronze medal to Canada after being disqualified over the second changeover in the 4x100m relay.
Dwain Chambers crossed the line third but the change between Harry Aikines-Aryeetey and James Ellington took place outside the designated box.
Canada was then awarded third place on appeal.
"It's heart-breaking," Aikines-Aryeetey said. "We found out when we were walking to the medal presentation."