He was stripped of his belt for being inactive and Nurmagomedov subsequently won the 155lb title by beating Al Iaquinta as the Russian extended his winning record to 26 straight fights.
McGregor was of course last seen in the boxing ring as he was well beaten by Floyd Mayweather but he is clearly eager to head back to the Octagon to regain what he believes is rightfully his.
McGregor, who once held two titles in the UFC, led a band of associates into Barclays Center in Brooklyn in April and vandalized a bus occupied by Nurmagomedov and other UFC fighters.
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McGregor hasn't fought within UFC since November 12, 2016 against Eddie Alvarez and he will be desperate to light up the sport once again.
As it played, Diaz abruptly left the presser he was at and tweeted "I'm not fighting on that show (expletive) the UFC".
Earlier in the news conference, the UFC also promoted the long-awaited return of Nate Diaz, who memorably split two bouts with McGregor in 2016. If there was any doubt that he would return to the UFC, that doubt is now gone. "I don't know why nobody told you guys that". Diaz vented his frustration that White supported McGregor while the Irishman was going through a similar circumstance with Showtime and Mayweather, but that White didn't give him the same support in public and also claimed that Diaz was turning down fights.
It was announced on Friday night that the controversial Irishman's grudge match with Russia's Khabib Nurmagomedov will be the headline act on October 6 in Las Vegas. In the interim, Khabib Nurmagomedov has taken the lightweight division by storm.