This is a tough fight to predict. Ultimately, the best way to predict the outcome comes by looking at each man's record against similar opponents.
Tibau has met finesse strikers with dangerous jiu-jitsu before in the form of Jim Miller and Rafael dos Anjos. Neither bout was a blowout, although Tibau lost decisively to Miller. His split-decision win over dos Anjos came by the narrowest of margins.
Dunham has squared off with great wrestlers before. In fights with Nik Lentz and Sean Sherk, Dunham was able to remain on his feet and use his striking advantage to dominate both men.
Expect this fight to be contested mainly on the feet. Dunham will look to keep this fight standing in hopes of staying out of bottom position against his heavily muscled opponent. That will lead to a bloody encounter between two lightweights who don't know how to give up.
Dunham will threaten with submissions to return to his feet in the event that takedowns do occur. For that reason, this is his fight to lose.
Prediction: Evan Dunham defeats Gleison Tibau via decision
Author's Note: To any Wikipedia fans who are going to say "but Dunham lost to Sean Sherk," it is important to note that Dana White called that decision a robbery. Evan Dunham was clearly the superior fighter that night who did not deserve to see his flawless record receive a blemish.