Chinese athletics icon Liu Xiang suffered more Olympic pain on Tuesday as he crashed out in the opening round of the 110 metres hurdles.
The 29-year-old, who four years ago withdrew from the event in front of his home crowd before his opening heat in Beijing, hit the first hurdle with his left leading leg and crashed to the floor.
Former Olympic champion Liu, who had been affected by back and foot problems in the past month, eventually got up and hopped down the track to be embraced by his fellow competitors.
He was helped off the track by Britain's Andy Turner and Spain's Jackson Quinonez and then taken away from the arena in a wheelchair.
Fellow competitor Balazs Baji of Hungary had waited for Liu at the finish line, taking the Chinese star's hand in his.
"When I was a kid I saw him breaking a world record, winning the Olympic Games in Athens so he's a great idol for me. I'm sorry that he fell. It must be really bad for him," he said.
"Since he fell I'm just sorry for him."
American Aries Merritt, the leading hurdler this season, said he felt sorry for Liu but didn't see anything untoward about him physically at the warm-up.
"It was just terrible. For that to happen to one of the best hurdlers of all time is just a tragedy and I hope he's OK," said Merritt, whose achievement in running the fastest ever Olympic heat of 13.07 was overshadwed by Liu's distress.
"He looked fine before the race, like nothing was wrong with him. He warmed up great. He always has a good warm-up and he was happy and so I don't think anything was wrong with him going into the race.
"I just think he made a small, little mistake, like he ran up on the hurdles a little bit too quickly and he wasn't prepared to take the hurdle at such velocity and he hit it and if you hit a hurdle in the fashion that he hit it there's no way to recover from something like that."
Liu's dream of winning gold in front of his home crowd at the Beijing Olympics in 2008 ended in one of the great Olympic anti-climaxes as he turned up for his heat but failed to clear a hurdle, clearly hindered by his Achilles tendon injury.
His career has been hampered by injuries ever since he took gold and equalled the then world record held by Colin Jackson of 12.91 seconds at Athens in 2004.
He was to go on and better it with a time of 12.88 seconds and also win a world title in 2007 but a succession of injuries have taken their toll.
However, he showed the old spark in the world championships last year and was flying when he was twice hindered by 2008 Olympic champion Dayron Robles and ended up third only to be promoted to second when the Cuban was disqualified from top spot.