EUGENE, Oregon (AFP) - Liu Xiang's disqualification from the Prefontaine Classic after a one-two Chinese false start Sunday underscores a disappointing US trip in the run-up to the Beijing Games.

The Olympic and world champion returns to his native China this week after a two-week trip to North America where he pulled out of one race and was disqualified from the other.

Liu was disqualified after posting the second false start in the 110 metre hurdles on Sunday in front of a crowd of about 13,500 at the University of Oregon track.

Starting from lane number four, Liu clearly rose out of the starting blocks first. Moments earlier Liu's Chinese teammate Shi Dongpeng had also jumped the starter's gun.

Shi was not disqualified because international track rules allow for one false start before the second offender is thrown out.

Shi finished last with a time of 13.50 seconds close to a half second behind winner Anwar Moore of the United States.

Liu and NBA star Yao Ming are the two most recognizable sports icons in China and injury scares to both have put the country's officials and sports fans on edge ahead of the Summer Games.

Liu, who is China's best hope for athletics gold at the Beijing Olympics, travels with a large entourage of coaches, trainers and Chinese minders.

He missed out on 5,000 dollars in prize money that goes to the first-place finisher in each of the 21 Prefontaine events.

Following the race, Liu tried unsuccessfully to sneak away without speaking to reporters by leaving the track through a back gate.

Liu's team was clearly perturbed by Sunday's chain of events. One of his minders -- acting as a translator -- refused to relay questions being directed at Liu by English-speaking journalists.

Asked to rate Liu's chances of competing or not competing in Beijing based on his leg injury the translator declined to pose the question to Liu.

Liu, who holds the world record of 12.88 seconds, had hoped to use his US races as a tune-up for the Beijing Games, August 8-24.

"Our plans have changed," said Chinese national team coach Feng Shuyong.

Feng said Liu would run one or two domestic races in China before the Summer Games.

Liu's participation in the Prefontaine had been in question up until race day. After arriving in North America on May 27, he pulled out of the New York grand prix event two weeks ago with what his coaches described as a hamstring problem.

Liu first noticed problems with the hamstring last month at a meet in Osaka, Japan said Feng.

He received treatment in Los Angeles and then flew to Portland where he saw Chinese specialist Yang Shizeng who used to work at the national sports institute in China.