Undefeated UFC lightweight champion Khabib Nurmagomedov on Monday confirmed reports of his father being in critical condition due to the coronavirus.

Speaking on Instagram in Russian, Nurmagomedov, 31, confirmed his father, Abdulmanap Nurmagomedov, recently underwent heart surgery due to complications stemming from a previous ailment and the coronavirus. He went on to encourage people around the world to remain in self-isolation to combat the pandemic.

"In my personal case, I've had more than 20 people sick from my family," Nurmagomedov said in comments translated by ESPN. "More than 20 people were lying in the ICUs. And many of them are no longer among us. Many acquaintances have died, many parents of my relatives. Everybody is having a hard time dealing with it.

"There is a lot written on the internet about my father. My father, right now, is located in a hospital. He is in critical condition as a result of this virus. It impacted his heart, because last year he had a surgery there and right now, they did another surgery. He is in a very difficult situation, very difficult. We are asking Allah that he returns him to us."

Abdulmanap is widely credited by Nurmagomedov, U.S.-based coach Javier Mendez and manager and friend Ali Abdelaziz as the main force behind his son's career. He is responsible for getting Nurmagomedov into the sport of wrestling at a young age.

Khabib Nurmagomedov, who lives in Dagestan, is a devout Muslim and currently is observing Ramadan, a religious fasting period. He encouraged Muslims to observe the end of the Muslim holiday in the absence of guests, rather than the traditional gatherings.

"Our learned Islamic scholars are telling us, 'Stay home and do the holiday prayer,'" Nurmagomedov said. "'Don't have guests. Don't go yourselves as guests.' It is a very difficult situation."

Nurmagomedov (28-0) was scheduled to defend his 155-pound title against Tony Ferguson at UFC 249 on April 18, but he was forced to withdraw from the bout because of travel restrictions out of Russia. He eventually was replaced in the fight by Justin Gaethje, who went on to defeat Ferguson and claim an interim lightweight title.

Nurmagomedov has not commented on a potential fight date because of his father's condition. UFC president Dana White, who over the past week has made several public comments wishing Nurmagomedov's father the best, has said he's targeting a fight between Nurmagomedov and Gaethje for September.