UFC lightweight champion Khabib Nurmagomedov looks more and more like an unbeatable fighter every time he steps into the cage. The Dagestani champion is 27-0 overall — the mark of a puzzle that has not yet been solved.

While it’s getting more and more difficult to imagine anybody beating Nurmagomedov, his head coach Javier Mendez believes there are fighters out there with the skills to test the champ — four lightweight fighters in particular.

Speaking to SportsDaily.ru recently, Mendez named four of the most compelling challenges for Khabib Nurmagomedov, ranking them from least to most dangerous.

He sees UFC featherweight champ Max Holloway as the least dangerous of the bunch. Next up is interim lightweight champion and Nurmagomedov’s next opponent Dustin Poirier. The second most dangerous opponent for Nurmagomedov, Mendez believes, is former interim champion Tony Ferguson and his slicing elbows. He believes the most dangerous opponent of all remains Conor McGregor, the slick boxer Nurmagomedov defeated by submission at UFC 229 in October.

“Talking about four potential rivals for Khabib I can give my assessment from the [least] dangerous to the most dangerous,” Mendez said of Nurmagomedov (via MMA News). “Max Holloway [would] be the easiest for Khabib. Max has good boxing but it lacks the power to the lightweight division. Next on the list is Dustin Poirier. He’s got stamina and versatility. Tony Ferguson is my second choice. His elbows are very dangerous. And finally [the] number one contender for me is still Conor. His boxing is special, that’s his chance.”

As aforementioned, Khabib Nurmagomedov is currently expected to defend his title against Dustin Poirier at UFC 242 in September. Tony Ferguson, meanwhile, is set to fight Donald Cerrone at UFC 238, while Max Holloway is set to defend the featherweight strap against Frankie Edgar at UFC 240. Conor McGregor, finally, does not currently have a fight booked.

This article first appeared on BJPENN.COM on 5/19/2019.