UFC 194: Aldo vs. McGregor was a mixed martial arts event held by the Ultimate Fighting Championship on December 12, 2015, at the MGM Grand Garden Arena in Las Vegas, Nevada.

However, the MGM Grand Garden Arena had already been booked for an Andrea Bocelli concert, prompting the UFC to look at alternative venues such as the Mandalay Bay Events Center.

The AT&T Stadium in Arlington, Texas was the most relevant venue under consideration, which would likely have made the event the highest attended in the promotion's history.

[6] Subsequently, on August 10, UFC president Dana White confirmed the event would take place at the MGM Grand Garden Arena, albeit one week later on December 12.

Instead of the MGM Grand Garden Arena, the other two events were held at The Chelsea at The Cosmopolitan.

[14] On January 13, Romero was informed of a potential doping violation stemming from an out of competition test conducted by USADA.

His team and USADA discussed a deal for a nine-month suspension for the fighter, but Romero preferred to go to arbitration.

USADA revealed that Romero tested positive for ibutamoren, a growth hormone release stimulator.

As Aldo fell to the ground, McGregor connected with two hammer fists until the referee (Big John McCarthy) stepped in to stop the fight.