The Chinese press have accused the team of match-throwing, following their 2-0 defeat in the Group C game in Gwangju on 4 June.
But Zhiyi, who is currently on loan to Cosco Shanghai Zhongyuan, has furiously denied the claims.
Anyone who knows me knows that I would never accept money to throw a match
The former captain and Asian player of the year said he is getting legal help from Zhongyuan to clear his name.
"The false reports have brought much distress to my family," he said.
"It is very unethical to print unsubstantiated reports just to boost circulation.
"Anyone who knows me knows that I would never accept money to throw a match.
"I will never tarnish the country's honour for any amount of money and the truth is I carried an injury into the Costa Rica match.
"I will fight for my innocence and Zhongyuan are in the process of finding me a lawyer to help me clear the smoke."
Fan played in the game against Costa Rica but then aggravated an injury to his left foot and so played no further part in China's disappointing World Cup campaign.