According to Russia's official state news agency TASS, a source revealed that Emelianenko is in hospital but should be discharged soon. 

"Fedor has been hospitalised with a positive coronavirus case," the source said. 

"There are no critical problems. 

"He is feeling well."

Emelianenko seemed to confirm the news when he posted a message thanking well-wishers on his Instagram. 

"Thank you all who are sincerely worried about my health," he said. 

"I am feeling well now, I am on the mend.

"I am grateful to the doctors and medical staff for their care and your hard work."

The 44-year-old, nicknamed "The Last Emperor", has had notable achievements across MMA, combat sambo and judo. 

In MMA, Emelianenko has a record of 39 wins and six defeats in his 19-year career and was the MMA Pride Fighting Championships heavyweight champion from 2003 to 2007. 

He also earned world titles in the combat sambo heavyweight division in 2002, 2005 and 2007, and claimed two bronze medals at the Russian Judo Federation National Championship in 1998 and 1999.

Emelianenko took a hiatus from professional sport between 2012 and 2015, during which time he was Russian MMA Union President. 

Russia has been one of the countries worst hit by the coronavirus pandemic, reporting more than 3.7 million cases and just under 70,000 deaths.