By Gene Cherry

RALEIGH, North Carolina (Reuters) - China's out-of-form former Olympic champion Liu Xiang can still be a contender at the 2012 London Games, according to veteran American hurdler Allen Johnson.

"I don't see why not. It's still two years away," Johnson, the 1996 Olympic 110 meters hurdles gold medalist, told Reuters in a telephone interview from his Irmo, South Carolina training base on Wednesday.

"(Liu's problems) will pass in time, it's just a matter of working through," said Johnson, who like Liu underwent tendon surgery in 2008.

"A surgery like that, you are going to be 90 per cent (recovered) within the first couple of months. But to get back to where you were before, it's going to take a good two years," said the 39-year-old Johnson.

"I am still recovering. My (left) ankle probably will never be 100 per cent," said the four-time world outdoor champion. "I limp every morning when I wake up.

"If he (Liu) is going through anything like what I went going through, I'm not surprised he has having some residual issues. "

Liu, forced out of the 2008 Beijing Olympics by an Achilles injury, has seldom been at top form since his surgery.

He lost to a compatriot for the first time in a major competition at the Shanghai Diamond League meeting last month and said after the third-place finish that London felt like a distant story.

"I just need to start with the most trivial things in my training without expecting too much for London," said the 2004 Olympic champion and former world record holder.

Desire will play a big role in any Liu return, Johnson said.

"He will come back if he wants to," said the American, whom Liu has long admired. "He ran 13.15 last September. So he still has it.

"Hurdling is something that you can do for a long time.

"As long as your heart is still there and you are willing to put in the work, you can always come back and be a factor."

(Editing by Greg Stutchbury)