Khabib Nurmagomedov will defend his lightweight title against interim champion Justin Gaethje in Saturday's UFC 254 main event in Abu Dhabi, United Arab Emirates.
Here are four key storylines heading into the pay-per-view event.
Many believe that if anyone can beat Nurmagomedov at 155 pounds, it's Gaethje.
Gaethje possesses the perfect style to pull off the upset and hand Nurmagomedov his first professional loss. He's a technical brawler with power in both hands and a former NCAA Division I All-American collegiate wrestler, and, most importantly, he never takes a step backward in the Octagon.
"The Highlight" is known for his pressure and aggressiveness, and that could be crucial in preventing Nurmagomedov's takedowns. The champion takes advantage of the Octagon better than perhaps anyone else and uses his opponent's backward movement toward the cage to inevitably get them down to the mat.
Twenty-eight people have stepped up to fight Nurmagomedov, seemingly knowing exactly what he was going to try to do, and he's taken down and smashed every single one of them. From Conor McGregor to Dustin Poirier to Al Iaquinta, there's been no stopping the lightweight king.
Gaethje is the next person who will try to halt Nurmagomedov's reign. He knows what the champion is going to try to do and appears to have the attributes to stop him. If Nurmagomedov is going to lose, it will happen on Saturday.
Nurmagomedov is one of the most dominant fighters in UFC history; he's lost a grand total of one round in his 12 fights with his promotion.
Gaethje may pose the biggest challenge thus far, but the champion is still a 3-1 favorite. If Nurmagomedov goes out on Saturday and does to Gaethje what he has to everyone else, what would he have left to prove?
The Tony Ferguson fight will always be appealing to fans, and UFC president Dana White recently said he'd still be willing to book it if Ferguson wins another fight.
Beyond that, though, nothing stands out as a particularly interesting matchup at 155 pounds. (Charles Oliveira could be an intriguing opponent because of his jiu-jitsu skills, but there's no chance we see that fight.)
The only bout the champion has serious interest in after Gaethje is a superfight with Georges St-Pierre, who said he would consider coming out of retirement only to face Nurmagomedov.
There have been suggestions that Nurmagomedov could retire after his 30th pro fight, and White said he would be open to booking the St-Pierre matchup as the Russian's retirement bout.
Nurmagomedov could always continue fighting the next challenger in the lightweight division. He could fight the Oliveiras, Dan Hookers, and Paul Felders of the division, but, assuming he keeps his title against Gaethje this weekend, it's more likely we see "The Eagle" compete in one or two more blockbuster fights and then ride off into the sunset.
Middleweight champion Israel Adesanya said after his title defense against Paulo Costa in September that he wants to face Jared Cannonier if "The Killa Gorilla" beats Robert Whittaker at UFC 254.
Cannonier is 3-0 since moving to the 185-pound division - including a second-round upset of Jack Hermansson - and seems like a lock for the next title shot if he beats the former champion.
But the title picture gets a bit foggy if Whittaker wins, because the Australian is only 13 months removed from his title loss to Adesanya. "The Last Stylebender" knocked him out in what was one of 2019's best performances, and fans aren't clamoring to see Adesanya-Whittaker 2 this soon after the first meeting.
That said, the UFC won't have much of a choice but to run that fight back if Whittaker beats Cannonier. The only other option would be Hermansson if he defeats Darren Till in December, but that means Adesanya would have to wait a while before making his next title defense, and he's expressed an interest in a quick turnaround after stopping Costa in the second round.
There's no doubt Whittaker would secure a title shot if he finishes Cannonier, as such a result would help sell him as the No. 1 contender. However, regardless of how the fight plays out, the UFC may have no choice but to book the rematch.
A pair of heavyweights looking to get back on track will collide on the UFC 254 main card.
Alexander Volkov and Walt Harris, who are coming off losses to Curtis Blaydes and Alistair Overeem, respectively, will fight for divisional relevance. Volkov is No. 7 and Harris is No. 10 at heavyweight.
The winner will be part of the UFC's list of top-tier heavyweights, which includes Francis Ngannou and Jairzinho Rozenstruik, while the loser will sit in the bottom half of the top 15 with the likes of Aleksei Oleinik and Marcin Tybura.
Heavyweight isn't a stacked division, so it'll still be possible for the loser to bounce back eventually. But in the immediate future, only one of these fighters will be considered a legitimate contender.