"UFC has a rule of thumb that if there is a championship fight on a card, it is the fight promoted the hardest, it is the fight the show is pushed synonymous with, and it goes on last, in the main event position. Most often, that's simply logic. The title fight is, more than 90 percent of the time, going to draw the buyers and have the most interest. While there are outliers, like big grudge matches that can garner more interest than a title match, they are rare. In those cases, UFC has almost always gone with the idea of sticking to tradition and presenting the title match as the main event."
"And UFC's biggest fights, historically, have been a combination of title match and grudge match, whether it's Brock Lesnar vs. Frank Mir or Randy Couture, Tito Ortiz vs.Chuck Liddell, Georges St-Pierre vs. B.J. Penn or Nick Diaz, or Anderson Silva vs.Chael Sonnen."