UFC 100 on July 11, 2009 at 7pm central time.
The event included two championship bouts and a fight between the two coaches on the Spike TV show, The Ultimate Fighter.
The main event was a rematch between UFC Heavyweight Champion Brock Lesnar and Interim UFC Heavyweight Champion Frank Mir. This championship unification bout occurred as a result of former UFC Heavyweight Champion Randy Couture’s year-long resignation from the promotion. During his absence, the UFC created an Interim championship, which Antônio Rodrigo Nogueira won by defeating Tim Sylvia.
Nogueira and Mir were opposing coaches on The Ultimate Fighter: Team Nogueira vs Team Mir, and fought for the interim championship at UFC 92. During the airing of the television program, Couture returned to the company and UFC President Dana White announced he would defend the title against Lesnar at UFC 91.
The winners of the Couture vs Lesnar and Nogueira vs Mir matches would fight for the undisputed title. In his fourth professional fight, Lesnar defeated Couture via technical knockout to become the UFC Heavyweight Champion. Mir was crowned interim champion after becoming the first fighter to finish Nogueira.
The match between Lesnar and Mir was set for UFC 98. However, Mir injured his knee while training, and withdrew from the bout. The next day, it was announced the fight would be moved to UFC 100.Lesnar and Mir had fought once before, at UFC 81 (Lesnar’s UFC debut); Mir won via kneebar submission.