The event was expected to be headlined by a 145 lbs UFC Featherweight Championship bout between current champion José Aldo and top contender Conor McGregor. Aldo pulled out of the bout and a interim championship bout between Chad Mendes and McGregor took place at this event. The UFC received official medical confirmation from several doctors that Aldo did not have a broken rib as he claimed and the biggest problem was the weight cutting process being complicated by the injury. This was confirmed when a release of an Xray tied to an old injury was released by Aldo's camp. The co-main event featured a 170 lbs UFC Welterweight Championship bout between current champion Robbie Lawler and top contender Rory MacDonald. 145 lbs: Dennis Bermudez vs. Jeremy Stephens | 170 lbs: Gunnar Nelson vs. Brandon Thatch | 135 lbs.: Thomas Almeida vs. Brad Pickett