The Edinburgh bantamweight was due to face Armenian Narek Abgaryan on the undercard of Dereck Chisora's rematch with Joseph Parker on Saturday, but has pulled out of the contest citing injury and personal reasons.
British champion McGregor is currently in Dubai and will step up his rehabilitation on a hand issue over the next few weeks in hope of returning to the ring early in the new year. However, the 24-year-old also revealed that his world was turned upside down upon learning his dad, Stuart, had been taken to hospital in a critical condition after being struck by a lorry in the Gorgie area of Edinburgh last month.
"I've had a really tough couple of weeks to be honest and my head has been all over the place," McGregor explained. "I've done some damage to my hand but I've tried to just train through the injury. It's nothing too serious. I might have been able to fight but the news of my dad being run over by a lorry and then being put in intensive care fighting for his life was just too much.
"I left Vegas as soon as I could to get home and see my dad. I actually read about the story online about someone being hit by a lorry but, at the time, I had no idea it was my dad.
"He's suffered a lot of broken bones but the main thing is he's alive. I'm glad he is still here to be honest. We're now working on a new date and looking at what's the best option. Hopefully it won't be too long."