McGregor, 29, reached the summit of the lightweight division in November 2016 in the main event of UFC 205, a card which saw him create history by becoming the first fighter in the promotion's history to hold two titles simultaneously. 

The Irishman hasn't set foot inside the Octagon since that historic night at Madison Square Garden, much to the frustration of many in the lightweight division. 

His hiatus from mixed martial arts, which was in part down to his multi-million-pound boxing match with Floyd Mayweather Jr, resulted in the UFC bringing an interim lightweight title into the mix. 

Several months have passed since McGregor's unsuccessful boxing debut and he has yet to convince the MMA world that he does indeed plan on defending his title. 

Mendez, like many of McGregor's critics, doesn't foresee that happening and views interim lightweight champion Tony Ferguson as the 155lbs division's undisputed ruler. 

"Khabib is probably the rare breed that wouldn’t wait for Conor. He doesn’t care if he fights Conor, he wants to fight for the title," Mendez told Express Sport.

"As far as he’s concerned and as far as I’m concerned, Tony is the legit titleholder. He is the legit champion, as far as I’m concerned. Because Conor isn’t going to defend it. 

“Conor is in the entertainment money business now, because he earned that right. Conor is where he wants to be. And it’s not to defend the lightweight title. He’s out there to make the biggest paydays available to him.

"And Conor is the boss, no one is the boss of Conor. Conor is the boss. So whatever Conor wants to do, he’s going to do. But defend that title, that’s not something that’s on the cards for him. 

Mendez believes McGregor's desire to make as much money as possible before hanging up his gloves will result in him never defending his lightweight crown.

He added: ”He wants more money and more of what’s coming his way for what he’s earned. And that’s what Conor’s going to do. 

“I don’t think he’ll ever defend the lightweight title. Unless it gets to that point where he really wants to Tony. 

“But, you know, when you’ve got Manny Pacquiao calling you out and Oscar De La Hoya calling you out, and then there’s also the possibility of a Mayweather rematch, because you’ve been hearing little rumblings, who knows. 

"You might see a rematch with one of the boxing guys again. And that’s a bigger payday for Conor, again.

"Outside of that, the next biggest payday would be Nate Diaz or GSP. A GSP fight would be very attractive financially for Conor."

Nurmagomedov can move a step closer to fighting McGregor this weekend in the co-main event of UFC 219, a card which will see him take on the always dangerous Edson Barboza.