The Eagle beat McGregor via submission at UFC 229 in October 2018 and the pair have shared an intense rivalry ever since.
McGregor is eager to face him again, but has been repeatedly denied.
Asked for his honest opinion on Nurmagomedov, he told a fan in a Twitter Q&A: “A phenomenal grappler fighter.
“The current best in the sport with it. I’ve the answer however and they know it.”https://platform.twitter.com/embed/index.html?dnt=true&embedId=twitter-widget-0&frame=false&hideCard=false&hideThread=false&id=1323001715680022528&lang=en&origin=https%3A%2F%2Ftalksport.com%2Fsport%2Fmma%2F783126%2Fconor-mcgregor-khabib-nurmagomedov-nate-diaz-dustin-poirier-next-fight-weight%2F&siteScreenName=talkSPORT&theme=light&widgetsVersion=ed20a2b%3A1601588405575&width=550px
UFC president Dana White, meanwhile, believes Khabib could come out of retirement to make it 30-0.
He said: “He was super emotional after that fight and you know he got the measles, the mumps, whatever he got.
“Then he broke his toe leading into that fight, took the fight, and with the passing of his father I just think he was super emotional and was just in the moment that night.
“I am not saying that he is going to 100 per cent come out for 30-0, but I get the feeling that he will.”
McGregor also retired from mixed martial arts earlier this year, but is expected to reverse that decision and take on Dustin Poirier.
The pair have met previously, in 2014, and McGregor actually hopes to improve upon that performance when he beat the American in less than two minutes in the opening round.
“I will aim to not only improve on the time I beat him in previously, but the shot I slept him with also! Poirier is a hell of a fighter, but I’m McGregor.”
He also revealed he is in better shape than when he beat Donald Cerrone in 40 seconds last January, but stressed he will meet Poirier in the lightweight division where he previously was champion.
“I will commit to the 155lb division for 2021. Some great matchups to be had here, as well as unfinished business. I will show the world once again who I am, and what I’m about.
“Trust that! 170 is in my thoughts also however. You know me for doubling up.”
A trilogy fight with Nate Diaz was also on the agenda and he was full of praise for the welterweight.
“Excellent fighter! The trilogy will be of epic proportions when it goes down.
“Nathan, and his fighting styles, are never far from my thoughts throughout my own practices. When it happens, I’m ready.”