4. Liu Xiang - most shocking withdrawal

Liu Xiang of China grimaces in pain during his warm-up before the start of his 110m hurdles heat of the athletics competition in the National Stadium at the Beijing 2008 Olympic Games August 18, 2008. Liu failed to start his 110 metres hurdles first-round heat on Monday. After one false start Liu stopped before the first hurdle clutching his leg and then walked out of the stadium.[Agencies]

Defending Olympic champion Liu Xiang of China pulled out of the 110m hurdles race injured, shocking the whole world.