US sprinter Tyson Gay doesn't know Chinese hurdler Liu Xiang at all, but he thinks they have something in common.

Injury prevented both from competing at the Beijing Games.

Both came back, strong and ambitious, for the London Games.

Both will go home from London extremely disappointed.

Liu ruptured his Achilles tendon in his heat, while Gay finished fourth in the 100m final and failed to bring home an elusive Olympic medal.

The 2007 world champion, Gay, who in 2011 suffered another injury and career-threatening surgery, said he empathizes with Liu.

"That was a bad story. I know the whole nation wants to see him run," Gay said on Wednesday. "He is the man to see on the television for Chinese and Asians. He had to do that for his country."

Gay said he hopes Liu -whose Athens Olympics gold in the 110m made him the first Asian man to win a track medal can pick himself up and keep fighting.

"That's hard. I think for years he's been a fighter," Gay said. "He is doing something strong like I have. He has to continue to fight, and he has to continue to run well. People in China and in Asia will see how he continues to fight and how he keeps running well. That will bring the sport a lot more push."

Gay's own comeback story could serve as an example for Liu.

After hip surgery last year, Gay enjoyed back-to-back victories at the Paris and London Diamond League meetings.

The 29-year-old Texan then ran 9.86 seconds at the US Olympic Trials to make it to London.

He said he gave his best at the Games. His 9.80 would have won every Olympic 100 ever run - before the era of Usain Bolt, that is.

Gay said Liu needs to take things one step at a time after surgery.

"(You have to get) mentally strong to do that," he said. "Have the plan; the plan about dieting, (how to) work out smarter and work harder.

"Do not worry about the practice and training after the surgery. But you must worry about trying to not make things worse. Do not rush, take it in time and stay focused on technique."

Gay said he faced additional pressure in London after failing to make the final in Beijing, where he suffered a hamstring injury in the 200m.

He is one of only three sprinters to have beaten world record holder and Olympic champion Bolt.

chenxiangfeng@chinadaily.com.cn