Rarely in the history of the UFC has a rivalry been quite so intense as that between Conor McGregor and Khabib Nurmagomedov.
Years of back-and-forth between the pair finally saw them meet in the octagon at UFC 229, where Khabib submitted McGregor in the fourth round of their lightweight championship contest.
However, the bad blood did not end at the conclusion of their contest - with the event ending on a sour note following a post-fight brawl involving members of both men's camps.
A rematch seems inevitable - and video has emerged of the duo's first face-to-face clash, showing that their dislike for one another dates back several years.
The footage was captured of the pair squaring off behind the scenes at UFC 205 in November 2016.
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Both men fought on the card at Madison Square Garden that night - with Khabib defeating Michael Johnson via third-round submission.
McGregor then went on to make company history by destroying then-lightweight champion Eddie Alvarez inside two rounds in the main event of the evening.
That victory saw McGregor become the first man to simultaneously hold UFC championships at two separate weights.
Their respective wins were not either man's only memorable moment from that evening though, as they became involved in a heated backstage exchange and needed to be separated by security.
Khabib is seen goading McGregor, before vowing to "smash" the Irishman in an eventual fight.
For his part, McGregor defiantly responded "we will see", before being ushered away.
The bad blood simmering between the camps of both fighters would then get worse in April of 2018 when McGregor attacked a bus on which Khabib and several other UFC fighters were travelling prior to UFC 223.
McGregor later revealed that his actions were prompted by an incident some hours earlier in which Khabib had assaulted his teammate Artem Lobov.
Tensions between all involved were at an all-time high by the time McGregor and Khabib eventually fought, with the animosity helping the event to reach 2.4 million pay-per-view buys.
It is perhaps unsurprising then that UFC president Dana White is exceptionally keen to see the fight again.
"When you look at what makes sense, he had lots of personal stuff going into the Khabib fight. He has been obsessed with getting that rematch.
"Khabib is 28-0 and you have to start talking about legacy. After tonight and after the first fight, we're looking at Hagler-Hearns, Ali-Foreman.
"This is a massive fight with global appeal. This is the fight to make. Masvidal doesn't have a world championship... Khabib is the fight to make," argued White.
Khabib seems clearly interested in a rematch.
Following McGregor's triumphant return to form against Donald Cerrone last weekend, the Russian posted an image to Twitter in which McGregor is seen losing by submission in each of the featherweight, lightweight and welterweight divisions.
The McGregor-Khabib feud may have started back in 2016, but looks sure to have several more chapters to run yet.News Now - Sport News