The UFC has had its fair share of intense rivalries over the years. It's almost impossible to pit two men against each other in the Octagon and expect anything less than a war, both physically and mentally.
Rivalries in the UFC have often become personal and - needless to say - violent, leading to a number of high-profile grudge matches. While some of these are yet to reach a conclusion, others have ended clearly in favor of one fighter despite being hotly contested.
Here are the 5 biggest grudge matches in UFC history.
Honorable Mentions: Tito Ortiz vs Ken Shamrock, Brock Lesnar vs Frank Mir, Rashad Evans vs Quinton 'Rampage' Jackson, Urijah Faber vs Dominick Cruz, Ronda Rousey vs Miesha Tate, Nick Diaz vs George St-Pierre
#5 Conor McGregor vs Nate Diaz 2 - UFC 202
After Diaz upset McGregor on short notice at UFC 196 in March 2016, 'The Notorious' was handed an immediate rematch. Scheduled for UFC 202 in August of the same year, McGregor vs Diaz 2 witnessed an entertaining buildup which included a number of personal jibes, jokes and schoolboy insults.
McGregor outlasted the Stockton native to avenge his earlier loss by securing a narrow UD win, and a trilogy seems inevitable at this point in time.
#4 Cody Garbrandt vs T.J. Dillashaw - UFC 217
Cody Garbrandt and T.J. Dillashaw seemed to be on a collision course immediately after the latter left Team Alpha Male. The fight became all but inevitable once Garbrandt became the UFC bantamweight champion with a masterful performance against Dominick Cruz.
After Dillashaw added fuel to the fire by claiming that he once made Garbrandt cry, 'No Love' hit back by saying that he knocked his former teammate out in a sparring session. The duo were pitted against each other on the 25th season of The Ultimate Fighter, with Dillashaw's infamous "betrayal" three seasons ago still fresh in memory.
The TUF season was heated throughout, and the face-off at UFC 217 had all the makings of an epic grudge match. It lived up to its hype, as Dillashaw handed Garbrandt his first professional loss with a smart combination in the second round.
The rematch, too, ended in favor of the 35-year-old Dillashaw, effectively putting a historic rivalry to an end - at least temporarily.
#3 Chael Sonnen vs Anderson Silva 2 - UFC 148
The meeting, in which Sonnen comfortably outclassed Silva on the mat for most of the five rounds, saw one of the greatest comebacks in UFC history. With the clock winding down in the final round, the UFC middleweight champ locked in a triangle armbar to submit his much less fancied opponent.
The historic fight set the stage for the rematch, but it wasn't the only contributing factor to the drama. Following his loss, Sonnen slipped in a few trademark quips and snide jabs, a few of which Silva didn't take too kindly to. The Brazilian labeled Sonnen a "criminal" and claimed that he'd "beat him up the way his parents should have."
Backing up his words, Silva came out on top in the rivalry by TKOing 'The Bad Guy' in the second round at UFC 148 in July 2012.
#2 Jon Jones vs Daniel Cormier 2 - UFC 214
One of the spiciest rivalries in UFC history, Jon Jones vs Daniel Cormier grabbed headlines during a turbulent time in the former's life. The first contest between the two, which happened in January 2015, ended in a comfortable UD win for Jones.
The bad blood was evident even before their initial meeting, with scuffles on stage and constant shots on social media acting as the perfect backdrop to Cormier's first career loss. But the underlying hatred truly manifested itself ahead of UFC 214, which hosted the rematch.
With a hit-and-run conviction and failed drug tests on the part of Jones marring his stellar UFC record, most fans favored DC. And although 'Bones' turned in a magical performance, knocking Cormier out in the third round, the loss was declared a No-Contest by the California State Athletic Commission.
We may never see a grudge match as charged (both inside and outside the Octagon) as Jones vs Cormier 2 in the UFC again.
#1 Conor McGregor vs Khabib Nurmagomedov - UFC 229
The biggest fight in UFC history in terms of PPV buys, Conor McGregor vs Khabib Nurmagomedov had everything a fight should, and a lot that a fight shouldn't.
Both men didn't really have much reason to instigate a feud with the other, but things escalated once McGregor vacated the lightweight title he won by knocking out Eddie Alvarez. Khabib had some choice words to say about McGregor's training partner Artem Lobov, before the infamous bus attack incident transpired.
The press conferences in the lead-up to the mega-fight were vulgar to say the least, with McGregor attacking his opponent's religion and nationality mercilessly. The stakes were never higher for the legacies of both fighters heading into UFC 229.
What followed was rather anti-climactic, as Khabib dominated McGregor before submitting him in the fourth round. The ensuing brawl outside the Octagon didn't help matters, laying the foundation for a rematch that promised to be even more marketable than the first meeting. Unfortunately, it wasn't to be.