Conor McGregor vs Nate Diaz video: Watch the moment Diaz inflicted McGregor's first defeat in the UFC

The win came with a second-round submission

Nate Diaz forces Conor McGregor into submission (2016 Rey Del Rio)

UFC featherweight champion Conor McGregor was choked into submission by Nate Diaz in a stunning reverse at the MGM Grand in Las Vegas.

McGregor, who was denied a chance to become the first fighter to hold two UFC belts at the same time when lightweight champ Rafael dos Anjos pulled out with a foot injury, struggled in the second round after Diaz landed a heavy blow.

McGregor had landed some heavy shots of his own in the first round but couldn't put the 30-year-old away, and an effort to take the fight to the mat backfired when Diaz got behind him to apply the rear naked choke hold that ended the fight.

WATCH: THE MOMENT DIAZ BEAT McGREGOR

"I thought I took him in the first round. I'm humble in victory or defeat," he said in the octagon after the fight. "I took a chance to move up a weight and it didn't work.

"I thought I landed with some good punches that got him off," a delighted Diaz said. "I started off slow but I'm faster than anyone later on. My jiu-jitsu is always there for me."