Conor McGregor lamented his inactivity after being stunned by Dustin Poirier at UFC 257 on Sunday.

The Irishman was knocked out in the second round by Poirier, the man he beat in September 2014, in Abu Dhabi.

But it was McGregor's first fight in 12 months and just his third since the start of 2018.

The former lightweight champion said his lack of competitive action was the difference.

"You know, it's hard to overcome inactivity over long periods of time and that's just it," McGregor said.

"The leg kicks were good, that low calf kick was good, the leg was dead and just wasn't as comfortable as I needed to be.

"It's the inactivity, but Dustin is some fighter and if you're in here, if you put in the time in here, you're going to get cosy in here and that's it.

"I have to dust it off and come back and that's what I will do."

McGregor said he was "gutted" and was keen to fight again this year.

Poirier, meanwhile, believes he is the lightweight champion – if Khabib Nurmagomedov (29-0) is unwilling to come out of retirement.

"I felt like this was a title fight," the American said.

"If Khabib's not coming back, me and Conor are the two best guys, I think this was a title fight. I'm the champion."