The highlight/lowlight came early this year with McGregor throwing a trolley dolly at a bus window during a media day in Brooklyn - Nurmagomedov was inside the bus. Furious UFC president Dana White said it was the "most disgusting thing...in the history of the company".
Days earlier, a McGregor teammate and Nurmagomedov argued in a hotel lobby. Nurmagomedov this week referred to McGregor as "some alcoholic guy" suggesting he used a lot of "drugs and whiskey".
Quotable quote:
"Conor is quite narcissistic, he cares about materialistic things and he wants more and more and more. Conor does his thing for marketing reasons." Fellow Irish fighter Myles Price, a former McGregor team mate, on his countryman's increasingly outrageous behaviour (USA today).
Who is Khabib "The Eagle" Nurmagomedov?
The 30-year-old is the first Russian and Muslim to hold a UFC title. He has a wrestling and judo background, and is undefeated in 26 fights with 10 knockouts. This is his first defence of the lightweight title.
Conor "Notorious" McGregor is...
The most famous MMA fighter on the planet. The 30-year-old former plumber from Dublin has 21 wins from 24 fights, with all three losses by submission. His last appearance in a ring was against undefeated boxing legend Floyd Mayweather jr., at the T-Mobile arena in August last year. Mayweather won the boxing contest comfortably, as expected, but McGregor acquitted himself pretty well. McGregor's last MMA fight was in late 2016.
The tape: At 1.78m, Nurmagomedov is slightly taller than McGregor, but the Irishman has a 10cm reach advantage.
"I think he is a man with a glass chin that hasn't been cracked yet...devastating, devastating KO. I hope it's not too early, to be honest. I believe I will clatter him, he will crumble."