Liu was clearly in pain as he tried to warm up for the 110m hurdles heats
China's defending 110m hurdles champion Liu Xiang has apologised to the Chinese people after injury forced him to pull out of the Olympics on Monday.
Liu's Athens Games win made him a Chinese icon but he managed just a few strides in the heats in Beijing before pulling up with an Achilles injury.
"I just feel so sorry," he was reported as saying by the China Sports Daily.
"Because there were so many people supporting me, I told myself I had to run, but I just couldn't do it."
The 25-year-old, the former world record holder in the 110m hurdles, was considered China's best hope for an athletics gold medal.
His early exit from the Games stunned the 91,000-capacity crowd in the Bird's Nest stadium and the shock was echoed around the country.
A Chinese presenter who broke the story on the Olympics TV channel's lunchtime (0600 BST) bulletin broke down in tears on air.
Liu, who had recently recovered from a hamstring injury, has endured ongoing problems with his Achilles tendon for several years and the injury flared up at the weekend before intensifying on Monday.
He said the pain was "unbearable" and added: "If I had finished the race, I would have risked my tendon. I could not describe my feeling at that moment.
"I never quit easily. I am not that type of person. I believe I will come back."