Conor McGregor sent a classy message to Khabib Nurmagomedov after reports the Russian's father and coach, Abdulmanap, was in a coma.
Abdulmanap, 57, was placed in a medically induced coma after complications from pneumonia, reports in Russia said on Wednesday.
McGregor threatened Khabib, the unbeaten lightweight champion, in an explosive Twitter rant on Monday, but put their feud aside to send his well-wishes to the Russian.
"Praying for the recovery of Abdulmanap Nurmagomedov," the Irishman wrote on Twitter.
"A man responsible for more world champions, across multiple fighting disciplines, than we even know. A true martial genius!
"Very saddened upon hearing this news tonight. Praying for the Nurmagomedov family at this time."
UFC president Dana White also offered his regards to Khabib and the Nurmagomedov family.
"Abdulmanap Nurmagomedov is a true martial artist who lives a life of pride, honour and respect," he said in a statement.
"He instilled those same values in his son, world champion Khabib, at an early age and was always in his corner throughout his career. I know how close Khabib is with his father and I'm saddened to hear about his current state.
"My thoughts are with Abdulmanap and the Nurmagomedov family as he continues to fight."
Khabib beat McGregor in an infamous bout in Las Vegas in October 2018, and is 28-0.