Conor McGregor has claimed bitter rival Khabib Nurmagomedov faked his dad's coronavirus illness to cover up pulling out of his fight with Tony Ferguson.
Abdulmanap Nurmagomedov has been struggling with Covid-19 in recent months and was placed in an induced coma in Russia.
His son was due to defend his 155lb title against Ferguson in April but Nurmagomedov Jr was unable to travel to the United States.
Instead Ferguson was beaten by Justin Gaethje who will now challenge the champion in September.
And McGregor, in a tweet which was then deleted, said: "I figured it was all just a cover up about Abdulmanap.
"A cover up to hide the lack of activity and the pulling out of fights and running away. Good luck but remember - Allah sees all!"
Nurmagomedov, who visits his father regularly in a military hospital, recently said: "His condition is still serious, he's still in intensive care.
"The coronavirus itself is behind him, but the virus has had consequences for his kidneys and his heart.
"As for the virus, there's no need to worry, only about the other consequences.
"I visit him, he recognises me, but there's no communication because he's connected to [medical] devices.
"Every day they let me in, I spend half an hour [with him], I hold his hand.
"When I ask: 'Father, do you recognise me?' He gestures and lets me know."
McGregor, who was choked out by Nurmagomedov in 2018, recently announced his third retirement from the UFC.
Frustrated by a lack of fights, the Irishman insists he will not return to the octagon where he was crowned a two-weight champion.
But he may well be convinced to return for a title shot against the winner of Nurmagomedov's clash with Gaethje.
