The reason we saw Conor sweating in that press conference trying so hard to get in Khabib's head, fumbling his words, seething with hatred, is because something exists in the back of his mind behind all the bravado where he knows he has been proven wrong multiple times in his career about the outcome of his fights and he was frustrated he couldn't knock Khabib down a peg because he is stronger than Conor psychologically. Conor also knows that if he loses it will likely be disastrously which adds even more pressure.
Khabib is not only undefeated, but believes he's being guided by a higher power and it's his destiny to win which actually takes a lot of the pressure off him because he believes someone else is responsible for his destiny if he puts the hard work in. Whether or not you are religious person, that puts him at a huge psychological advantage.