In the world of UFC - and in MMA, period - so often it's absolutely vital to have a great chin.
A slew of big-hitting powerhouses have been let down over the years due to the simple fact that they have a glass jaw - here's looking at you, Alistair Overeem - and the sport of MMA can at times be more about how hard a shot you can take rather than how hard a shot you can give.
Size and technique can be left redundant if a fighter has a chin that flakes on them after one good strike. In fact, certain fighters have flat-out made a career based around the faith they've got in their chin holding up against bomb after bomb.
There's a whole other level of toughness to having a granite jawline that does nothing but frustrate an opponent. But then again, many fighters see the opportunity to shatter a legendary chin as being one of the greatest challenges of being in the MMA game.
On that trail of thought, then, here are the ten greatest chins in the history of the Ultimate Fighting Championship.
10. Diego Sanchez
For Diego Sanchez, it took 12 years of his UFC career before somebody really broke past his stone-cold solid chin.
There had been a TKO stoppage and some decision losses along the way, but 2017's KO loss to Al Iaquinta was the first time that the Nightmare had been properly knocked out. Now 37 years of age, Sanchez has so often been an absolute glutton for punishment in his career.
The New Mexico-born fighter is one who loves nothing more than getting hit, moving forward, getting hit again, and again moving forward. Diego Sanchez has made a career of taking massive shot after massive shot, and key to the success of that approach is having a chin that simply refuses to give in.