British sprinter Tiffany Porter has withdrawn from the 100m hurdles event at the London Grand Prix with a back injury.
The American-born athlete had been struggling with the complaint for a number of weeks.
However, with the Crystal Palace meeting due to be the last chance for athletes to compete before the Olympics, the 24-year-old opted to compete in the opening heat in the English capital.
As a result, she has aggravated the problem, which is now expected to keep her out of action for around seven days.
She is the second British competitor to pull out of today's event following Phillips Idowu decision to withdraw with a hip injury.
