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
Conor McGregor
Chad Mendes
Robbie Lawler
Rory MacDonald
Jeremy Stephens
Dennis Bermudez
Gunnar Nelson
Brandon Thatch
Thomas Almeida
Brad Pickett
Matt Brown
Tim Means
Alex Garcia
Mike Swick
John Howard
Cathal Pendred
Cody Garbrandt
Henry Briones
Louis Smolka
Neil Seery
Cody Pfister
Yosdenis Cedeno