And now McGregor has said on Twitter that he sustained an injury in the lead-up to the eagerly-anticipated clash.
In response to a question on the social media platform, McGregor wrote: 'I broke my foot three weeks out from the bout.
'On his blood brother. I am happy with how the contest went and the lessons learned. In my fighting and more importantly my preparation. Time will reveal all.'
The fight six months ago descended into chaos with a post-bout brawl and both fighters were handed suspensions.
The Irishman was banned for six months and fined £38,000 by the Nevada State Athletic Commission while Khabib was suspended for nine months and given a £380,000 fine.
UFC star McGregor took to social media in March to reveal he is retiring from the sport of MMA.
CONOR MCGREGOR TIMELINE FROM DEBUT TO KHABIB DEFEAT
February 17, 2007: Conor McGregor makes his MMA debut against Ciaran Campbell and wins in the first round by knockout
March 9, 2008: McGregor makes his professional debut and beats Gary Morris in the second round
June 28, 2008: The Irishman's eagerness to build up his record sees him run before he can walk as he suffers his first defeat at the hands of Lithuanian submission expert Artemij Sitenkov
2009: In a surprise move, McGregor elects to take the entire year off from professional competition as he looks to focus on his technique
October 9, 2010: After almost two years out of the sport, McGregor makes a winning return against Connor Dillon in Chaos Fighting Championships
March 12, 2011: It takes McGregor just 16 seconds to knockout opponent Mike Wood and the referee steps in to end the non-contest
April 6, 2013: He makes UFC debut against Marcus Brimage in Sweden on preliminary card for Gegard Mousasi vs Ilir Latifi. The bout was stopped in the first round and McGregor won by knockout
August 17, 2013: McGregor backs up victory over Brimage by beating Max Holloway, only to tear his anterior cruciate ligament during the bout and he needed surgery, keeping him out of action for up to 10 months
January 18, 2015: After beating Dennis Siver, McGregor jumps out of the cage to confront Jose Aldo as the pair were to go head-to-head in Las Vegas in the Irishman's first world title shot
July 11, 2015: Aldo pulled out through injury and so McGregor went on to beat Chad Mendes for the interim featherweight belt
December 12, 2015: Finally he had the title shot he desired and given Aldo had not lost in years, McGregor's victory after 13 seconds set a new record for the fastest UFC knockout in a title bout. The bout generated 1.2m pay-per-view sales placing it as second highest in UFC history at the time
March 5, 2016: Having reached the peak with the world title, McGregor was brought back down to earth with a submission defeat by Nate Diaz at the MGM Grand in Las Vegas
August 20, 2016: Reeling from the loss, the Irishman swiftly agrees a rematch with Diaz and this time wins the contest by majority decision
November 12, 2016: Holding off from a trilogy bout so soon after gaining revenge on Diaz, McGregor takes on Eddie Alvarez and wins the UFC Lightweight Championship to become the first UFC fighter to hold titles in two different weight classes at the same time
August 26, 2017: After taking time out of UFC - seeing him stripped of his featherweight title in the process due to inactivity - for the birth of his first child, McGregor's notoriety saw him land a boxing contest with Floyd Mayweather. The Irishman lost but secured a $100m payday
October 6, 2018: Further inactivity saw him stripped of his lightweight title but he made his UFC return in Las Vegas for an eagerly-anticipated clash against Khabib Nurmagomedov which he lost. The fight descended into chaos with a post-bout brawl and both fighters were handed suspensions