BEIJING, China -- China's Liu Xiang, the defending gold medalist and world champion in the men's 110 meter hurdles, failed to get out of the first round of qualifying in the event Monday at the Beijing Olympics.

The early exit was a shock to the crowd at Beijing National Stadium as Liu had been China's best chance at a gold medal in the track and field competition at these Games.

Liu had been suffering from a hamstring injury and the ailment ended his gold medal defense before it ever began. He attempted to start the race, but pulled up lame after another runner false started in the sixth and final heat of the 110 hurdles. The Chinese national hero then walked off the track and disappeared into the tunnel, taking the hopes of his nation with him.

The hamstring injury has been hampering Liu for months now and forced him to pull out of a race in May.

Liu's exit should mean an easier route to gold for a strong duo of American hurdlers. David Oliver and David Payne of the U.S. both qualified for Tuesday's second round by winning their respective heats.

However, Terrence Trammell of the U.S. exited the 110 hurdles with an apparent leg injury, as he pulled up early in the fifth heat and failed to finish. Trammell won silver medals in the 110 hurdles at both the Sydney and Athens Games.

Cuba's Dayron Robles, world record holder in the 110 hurdles, also won his heat.

Meanwhile, fresh off claiming the title of World's Fastest Man, Jamaica's Usain Bolt qualified for the second round of the men's 200 meters Monday morning at the Bird's Nest.

Bolt won gold in the men's 100 meters Saturday evening, running the dash in a world record time of 9.69 seconds. He finished second in his opening heat of the 200 with a time of 20.64 seconds, the 17th-fastest time of Monday morning's qualifying round.

Bolt, who turns 22 years old on Friday, finished second in the 200 at last year's world championships. The Jamaican women also swept the 100 meters on Sunday night.

The United States sent all three of its entrants into the second round of the 200. Wallace Spearmon had the third-fastest time of the day, qualifying in 20.46 seconds. Shawn Crawford was the 14th fastest and Walter Dix, bronze medalist in the 100, finished 22nd.

Dix was the lone medalist for the U.S. on the men and women's side in the 100, a race the Americans usually count on for a few medals at every Olympics.

"It's getting better," said Dix about the mood of the U.S. track team. "The 400 guys got us up for the 200, that's USA's event, even though there's someone called Bolt."

Zimbabwe's Brian Dzingai ran the 200 in 20.25 seconds for the fastest time of the opening round.

The second round of the 200 will take place later on Monday.

The American sprinters also made it 3-for-3 in the opening round of the men's 400 meters, as LaShawn Merritt, Jeremy Wariner and David Neville all made it to Tuesday's semifinals. Merritt has the fastest time of the U.S. trio, running the track in 44.96 seconds.

Wariner is the defending Olympic and world champion at the distance, while Merritt took silver at last year's worlds and won the 400 at the U.S. Track and Field trials last month. The American sprinters have developed a healthy rivalry that could work to the benefit of the U.S. in this event.

"It helps to have a competitor that can run just as fast as you, just as strong," said Wariner. Christopher Brown of the Bahamas turned in the morning's fastest time of 44.79 seconds. Also on Monday morning, the Americans failed to qualify anybody for the finals of the men's triple jump and the women's hammer throw. Rafeeq Curry, Kenta Bell and Aarik Wilson bowed out of the triple jump, while Amber Campbell, Loree Smith and Jessica Cosby failed to move on in the hammer throw.

The evening session at the Bird's Nest will feature medal events for the men in the long jump, 400 meter hurdles and 3,000 steeplechase and the women will battle for gold in the pole vault, discus and 800 meters.