Liu Xiang's parents are under as much pressure as their son as he prepares to defend his Olympic 110 m hurdles crown, the couple said yesterday.

"We try not to think about the ‘what ifs,’" the sprinter's father Liu Xuegen said before the couple set off for Beijing from their home in Shanghai.

"We just hope he does his best."

Liu and his wife Ji Fenhua will attend today's opening ceremony and will stay in the capital to watch their son compete.

"We feel as anxious as any parents would if their child was facing such a tough test," Liu said.

We have received lots of calls from friends and relatives, and some of them even had advice for Liu Xiang, his father said.

"We understand how they feel, but we won't even get to see Liu Xiang ourselves anytime soon," he said.

The biggest pressure currently facing the 25-year-old hurdler is how to fend off the challenge of Cuban world record holder Dayron Robles, who has been running in top form. In June, he broke Liu's former world record of 12.9 seconds by one-hundredth of a second.

Liu's mother, however, said her biggest fear is that her son will suffer leg cramps from training too hard.

She said she calls him every day and tells him to be extra careful, but skirts the issue of how his training is going.

"Liu is under intensive training to compensate for the shortage of competitions before the Olympics," said Liu's coach Sun Haiping was quoted as saying recently by to the Chinese Athletics Association website.

Liu Xiang will begin the defense of his Olympic title on Aug 18.