Conor McGregor was among a host of UFC greats to take to social media to congratulate Khabib Nurmagomedov after the lightweight champion announced his retirement.
Khabib was fighting at UFC 254 for the first time since the death of his father and coach Abdulmanap Nurmagomedov in July following complications with coronavirus.
The Russian dominated interim champ Justin Gaethje with a second-round technical submission in Abu Dhabi to unify the division but then revealed it would be his last bout.
Khabib, who is 29-0, said he had promised his mother he would not continue his career without his father.
As the UFC reeled from the news, a number of its leading names sent messages to Khabib - including rival McGregor.
"Good performance @TeamKhabib," he wrote. "I will carry on.
"Respect and condolences on your father again also. To you and family. Yours sincerely, The McGregors."
Jon Jones, described by Dana White as "the greatest ever", added his best wishes, writing: "I want to congratulate Khabib for an outstanding career.
"I know he made his father along with millions of fans around the world incredibly proud today. May God continue to bless him on his journey."
Daniel Cormier said: "Congratulations to the greatest champion in @ufc history.
"What a career, we are forever grateful for the time we got to spend with you my brother. 29-0 undefeated and undisputed."