Robles easily won his Beijing heat less than an hour before Liu was scheduled to compete, while medal contender Terrence Trammell of the U.S. also failed to finish his race due to an injured leg.

"It's disappointing Liu Xiang is not here." Robles said.

Robles' record puts extra pressure on Liu, the reigning world and Olympic champion who is China's biggest hope for gold on the track at the Beijing Games.