London, Jul 28 (IANS): Liu Xiang must run within 12.95 seconds to win the men's 110-metre hurdles at the London Olympics, his coach Sun Haiping said.

"It is difficult for him to take the gold, but I will try to make him in best form," Sun was quoted as saying by Xinhua.

"American Aries Merritt will be a tough opponent and Liu must try his best."

Merritt has run in 12.93 three times in 2012. Liu's best time this year was 12.97.

Earlier Friday, Liu said he felt "most relaxed" in London.

"Compared with the Olympics in Athens and Beijing, I feel most relaxed in London," Liu said before the opening ceremony of the 30th Olympics.

"I have different feelings in attending the Olympics at different places," he said, "In 2004, I wanted to go into the eighth one while I felt more pressure in 2008 in my own country."

"I will be a success as long as I can enter the finals in London Olympics," he said.

The men's 110m hurdles in London Olympics will be held Aug 7-8.