3RD LEAD: More Olympic tragedy, and likely Achilles rupture, for Liu By John Bagratuni, dpa Eds: Adds byline, wraps up morning session with details, q

London (dpa) - Chinese athletics poster boy Liu Xiang suffered another Olympic tragedy on Tuesday by falling after the first hurdle of the 110 metres heats with a suspected Achilles tendon rupture - an event that overshadowed superstar Usain Bolt‘s return for the 200m.

Chinese athletics team leader Feng Shuyong named the injury in a hastily arranged, packed news conference, but said that further examinations will follow.

"The initial diagnosis from the medical staff is that he has a ruptured Achilles tendon," Feng said.

The incident came four years after the 2004 gold medallist limped out of the stadium at the home Games in Beijing before his heat, unable to run because of Achilles pain - sending shockwaves through the world‘s most populous nation.

Tuesday‘s exit and injury were also met with dismay, including from Jamaica‘s Bolt. He started his bid for back-to-back 200m titles with a comfortable heat win in 20.39 seconds, two days after getting successive 100m golds.

"It is really hard for him because I think he is one of the best, hands down. He has shown the world he can do great things. For him to push himself and come back ... for this to happen, this is really sad for any athlete," Bolt said.

American hurdles season leader Aries Merritt said: "It is just terrible for that to happen to one of the best hurdlers. He looked fine before the race and was in good humour."

Speaking before the injury was announced, Merritt added that he believed Liu had made a mistake by crashing his left foot into the hurdle. But television replays later showed that Liu never managed to lift the right foot off the ground to propel him over the hurdle.

He hobbled off the track and down to the finish line next to it, later helped by two other runners before being taken to the medical centre in a wheelchair.

Liu, 29, underwent surgery in the United States after the 2008 incident, changed his start technique, returned in 2010 and got silver at the 2011 world championships.

But Feng said the injury never really disappeared and that it got worse again during pre-Olympic training, when they simulated the tight Olympic schedule with three races in two days - and just two hours between the semi-finals and final scheduled for Wednesday.

"He has to simulate it in training. By doing this, the problem probably happened. He didn‘t have enough time to recover. But even in that situation we didn‘t expect it to happen like this," Feng said.

"When something like this (a rupture) happens, there is no sign before," he added.

Feng said that Liu is out for the season, but not wasting a thought on retirement. He praised his courage, saying Liu "showed true Olympic spirit."

There was dismay, but also sympathy in China over the latest setback for Liu. State news agency Xinhua reported that he had been wearing the same start number, 1346, as in Beijing.

Merritt led the 110m heats with 13.07 seconds for a place in the semis, with fellow American world champion Jason Richardson and the 2008 Olympic champion - and world record holder - Dayron Robles of Cuba also safely through.

Bolt didn‘t have to break a major sweat in his 200m heat and handily advanced, along with his Jamaican training partner Yohan Blake, who is seen as his main rival in the event. He clocked 20.38 seconds on Tuesday, one hundredth ahead of Bolt.

"Got to take it easy ... That was an easy run. I am enjoying it. This is my favourite event so I am looking forward to it," said Bolt, who got another rousing welcome from the packed stadium.

Meanwhile, the 10,000m champion Tirunesh Dibaba of Ethiopia topped the women‘s 5,000m heats with 14 minutes 58.48 seconds, remaining on course for successive long-distance double golds.

World champion Christian Taylor of the US led the men‘s triple jump qualification with 17.21m. British hope Phillips Idowu missed the final with 16.53m in the wake of injury.

In the women‘s javelin qualification, Czech world record holder Barbora Spotakova led the way with 66.19m.

The evening session‘s medal events are the men‘s 1,500m, discus and high-jump, as well as the women‘s 100m hurdles. dpa bag adh amh