Dana White revealed Khabib Nurmagomedov told him he was "so many levels above" his rivals, making it unlikely the undefeated star will come out of retirement.
Khabib (29-0) sensationally retired after beating Justin Gaethje in October last year.
White has been pushing for the Russian to return for a 30th fight, but that seems unlikely to happen.
After Dustin Poirier stunned Conor McGregor, the UFC president revealed he had a conversation with Khabib.
"I did talk to Khabib," White said.
"He said to me, 'Dana, be honest with yourself, you know I'm so many levels above these guys, I beat these guys.'
"I don't know, I don't know, but it doesn't sound very positive so we'll see.
"I told you guys before he won't hold the division up. He already retired, he's basically retired, I'm the one that's been trying to get him to do one more."
White confirmed McGregor and Poirier would likely fight for the lightweight title if Khabib did not return.