"Definitely, it's possible. You know, right now it's like this is a legacy fight for Islam. Why I really want him to fight vs. Charles Oliveira, because he had 11 win streak and UFC never make like this fight. 11 win streak vs. 10 win streak. It's supposed to be me versus Tony [Ferguson]. Ok, it never happened. Now we have Islam vs. Charles. Let these guys fight."

"If Islam beat Charles and then he beats new blood like from young generation, we have a lot of young fighters in lightweight division ranking. Beneil [Dariush], Islam beat Charles, Islam beat three more fighters, he can become the greatest lightweight ever. He has this potential. He's only 30 years old, but UFC has to give him chance."

That was the undefeated (29-0) UFC legends' answer when we asked if 30-year-old Makhachev could be the superior mixed martial artist.

Islam is the #4 ranked UFC lightweight ... and has been absolutely unstoppable since his one and only professional loss way back in 2015.

Makhachev has racked up 10 wins in a row ... beating guys like Dan Hooker and Drew Dober along the way.

We said Islam was Khabib's friend ... but that doesn't really do their relationship justice. The men have been close since childhood, and are more like brothers. They also train together at AKA (American Kickboxing Academy) in northern California.

Of course, Nurmagomedov's resume is well-known. 33-year-old Khabib, who is no longer fighting, beat everyone from Justin Gaethje, Dustin Poirier to Conor McGregor and just about every other badass 155-pound fighter on the UFC roster.

There's more.

While Khabib may be retired from fighting, he's anything but retired from working. In fact, his Eagle FC MMA promotion has a huge card Friday night featuring a few MMA legends.

Junior dos Santos is fighting Yorgan De Castro ... and Thiago Silva is fighting Hector Lombard.

"Definitely this is biggest card in Eagle FC history," Khabib told us.

"I'm very excited about this!"