"I admit like most of my countrymen, I too did not attach importance to the coronavirus," he said.
"We really underestimated the disease, we began to feel its danger and threat only when it knocked on our door."
"I myself transmitted it."
The four-time world champ suffered the sickness and has recovered, and now he's telling Russia and the world to be responsible and listen to advice from medical experts.
"We really underestimated the disease." - Sadulaev
His latest post asks for the "patience to overcome this test and learn from it."
Sadulaev comes from Dagestan in Russia's south-west, a region with a Muslim majority which has been hit hard by the spread of COVID-19.
And with the Eid festival that marks the end of the month-long dawn-to-sunset fasting of Ramadan, traditionally celebrated with big public gatherings, the wrestling superstar is urging people to respect social distancing.
"This is our only way out." - Sadulaev
"Celebrate at home"
"I want to urge you to celebrate at home," continues Sadulaev's message.
"We need to take care not only of ourselves but also people who are around us, especially our elders; and people with chronic illnesses suffer seriously.
"I understand that sitting at home for the third month is not an easy task, but we need to show a little patience.
"This is our only way out, relief comes after every burden."
Russia as a whole and Dagestan in particular has been overwhelmed by spikes in virus infections.
Sadulaev knows what it feels like and is now trying to warn others about the realness of the threat.
Rio 2016 champion, Russian hero
This Russian prodigy exploded onto the scene in 2014 by winning the 86kg world championships at just 18 years of age.
Earning himself the nickname 'The Russian Tank', he is considered by many watchers as the best freestyle wrestler in the world.
Two years after becoming world champion he grappled his way to Olympic gold at Rio 2016, overpowering Turkey's Selim Yasar 5–0 in the final.
Sadulaev was greeted as a national hero in Moscow on his return from Rio.
He has long maintained that his faith is key to his success.
Enjoy all of his Olympic matches, and more wrestling, right here: