Getting knocked out is perhaps the worst thing that can happen to a UFC fighter, especially when it doesn't even happen in professional MMA competition.
Over the years, UFC fighters have tried their hand at various martial arts disciplines outside the world of MMA. While some have used forms of combat sports as a stepping stone to the top level of mixed martial arts, others have chosen to test out new waters and challenge themselves.
In this article, we take a look at five UFC stars who got knocked out outside MMA. There are a variety of curious incidents on this list, involving boxing, kickboxing and even a confrontation that had nothing to do with a professional fight.
#5 Former UFC featherweight and lightweight champion Conor McGregor
Unlike the others on this list, Conor McGregor wasn't brutally knocked out, but his only professional boxing bout so far ended in a TKO loss.
In his boxing debut against Floyd Mayweather, 'The Notorious' saw the fight come to an end in the 10th round when referee Robert Byrd decided he had seen enough. McGregor was clearly hurt in the round as he repeatedly tried to clinch with Mayweather, who rained down combinations with accuracy and speed.
McGregor started well and performed better than many expected him to, keeping 'Money' on the backfoot and forcing him to alter his gameplan. But the Irishman faded a few rounds into the fight as Mayweather used his supreme cardio and boxing awareness to smartly take advantage of the situation.
Neither fighter was too unhappy after the bout as they pocketed sizeable paycheques, but it was the first knockout loss on McGregor's resume as a professional combat sports athlete. Mayweather, 40 years old at the time, extended his professional boxing record to an incredible 50-0.