One of those two is Saturday night's challenger, Quinton "Rampage" Jackson, who dethroned Chuck Liddell after a two-year reign at the top. At the time, Liddell was seemingly at the height of his powers. Though 37 years old then, he had finished seven straight opponents, and was installed as a massive favorite against Jackson.
Of course, Jackson went on to upset him in a first-round knockout before successfully defending the belt against Dan Henderson, then lost it in a close split-decision to Forrest Griffin.
At UFC 135, Jackson is back in the same role, a challenger facing long odds.
The current lines have champion Jon Jones as much as a 7-to-1 favorite. That's a shocking number considering Jackson's pedigree and history of success. The belief in Jones as a lock to win stems from his dominant performances so far, the excitement that has crested during his quick rise to the top, and his perceived matchup advantages against Jackson.
Chief among them is his reach. Jones will have nearly a one-foot reach advantage against Jackson, 84.5 inches to 73 inches. Given Jackson's tendencies to be a counter-fighter, he is bound to face some difficulties getting inside, where his hooks become his most dangerous weapons.
Jones has the size and length to stand on the outside and batter away at Jackson's legs the same way Griffin did when he beat Jackson in 2008. Because Jackson rarely checks kicks, and seldom fires back kicks of his own (only 12.5 percent of his standing strikes are kicks, according to Compustrike), that's an area of major concern. By comparison, kicks account for 39 percent of Jones' standup strikes.
Jones is also excellent at varying his areas of attack. He doesn't get caught up in head-hunting, as evidenced by his fight against Mauricio "Shogun" Rua, during which he softened up the then-champ with body shots throughout. That unpredictability is a key element of his success, but it also leaves openings.
That's where Jackson hopes to make his stand. Jackson has always been a patient fighter, waiting for his opponent to commit to him before firing back. As proof, it's telling that during his UFC career, he's gone 7-2 despite the fact that his opponents have thrown 170 more combined strikes than him. That's fairly rare for a winning fighter, let alone a former champion.
Being a counter-fighter causes you to pick your spots wisely, but it also leaves little room for error. Jackson is good at his style because he lands when he throws, connecting on 53 percent of standing strikes, an excellent ratio. But he's never faced anyone with Jones' reach, leaving questions about how effective his style can be here.
If things aren't going well for Jackson, he might have to wade inside, where Jones has shown a strong clinch game, alternately using it to deliver punishment or score takedowns. He's manhandled most of his opponents from in tight, and Jackson has had issues there in the past, making it murky waters to navigate.
All that leaves us with the same conclusion that everyone's had from the moment this fight was announced: Jackson's best chance of winning is hurting Jones with a hook. The odds suggest it is nearly impossible, but we must note that Jones has never faced anyone who fights like Jackson. Rua is the most similar opponent he's fought in terms of experience and power, but his style is quite different. Rua likes to come forward and be the aggressor, his standup is a Muay Thai blend, and he aggressively hunts the takedown. Jackson is none of those things. He's going to dare you to come to him, he values his hands above all his weapons, and he avoids the ground at all costs.
Despite the fact that Jackson hasn't had a knockout in his last four fights, he's dropped three of the four with punches, so to suggest his power isn't there is misleading. If Jones comes in with his chin untucked, or if Jackson finds the money spot, he's still capable of a finish. Jones has never really been in any kind of trouble, and he's never really been hit square. That is due to his own defensive abilities, but the fact remains that we can't be certain about how he'll take a big punch.
The biggest area of concern for Jackson is on the ground. Jackson has very good submission defense, but he never threatens from the bottom and struggles to return to his feet. Meanwhile, Jones has become a killer on top, utilizing his length and leverage to generate some of the most brutal elbow strikes in the game. If Jones can continually put Jackson on his back, Jackson has big trouble.
Jackson doesn't have the multi-pronged offensive approach that can shake a still young fighter. Once Jones gets his timing down, as his comfort level in evading Jackson's counterpunches grows, the odds will grow longer for Jackson. To say he has virtually no shot as the current odds indicate is untrue. His punching power is still there, his hands are still relatively quick, his punches are tight, and he's got experience on his side. But a lot of what he does should play right into Jones' hands. He's going to let Jones throw first, which is bad. He might counterstrike his way into Jones' clinch, which is bad. And any attempt to get inside might lead to a clinch and/or takedown, both of which are bad.
Jones has many more ways to win, and I think he wears down the challenger over time with leg kicks, body shots and ground work. Jackson has always been a durable fighter, and that will be put to the test here, because there will be plenty of stuff coming at him. Jones via fourth-round TKO.