Ranking the Biggest Losses of Conor McGregor's Career
Former two-division UFC champion Conor McGregor is less than a week out from a showdown with fellow lightweight contender Dustin Poirier. The fight, which headlines the UFC 264 card on July 10 in Las Vegas, will mark the third time the two lightweight stars have met.
McGregor won their first encounter, a featherweight fight back in 2014, by first-round knockout. Poirier then evened the score with a blistering, second-round knockout win at UFC 257 in January of this year, this time at lightweight.
It was a jarring setback for McGregor—one that erased most of the work he'd done in a 2020 drubbing of Donald "Cowboy" Cerrone—and it raised legitimate questions about his place among the sport's top lightweights.
But where did that loss rank among the other professional setbacks of his long and illustrious career? Keep scrolling for our take.
6. Floyd Mayweather Jr.
If the significance of a loss was based solely on the number of people who saw it happen, this one would take the top spot on our list.
When McGregor stepped into the boxing ring for a fight with Floyd Mayweather Jr. back in 2017, there were 4.3 million people watching on pay-per-view, and surely millions more tuned in illegally. All of those people—save the ones who took ill-timed bathroom breaks—watched McGregor wilt under a storm of Mayweather punches in the 10th round.
The reason this loss appears at the bottom of our list is that it was predictable. Extremely predictable. While McGregor's immeasurable self-belief and crackling knockout power made things somewhat interesting, the reality is that he was taking on the best boxer of a generation in his first professional boxing match. A Mayweather win was all but a certainty.
Furthermore, McGregor definitely benefited from this loss. Not only did he take home a career-best payday for his efforts—by a significant margin—but the fight also elevated his superstardom to new and unprecedented heights.
Really, it's hard to even call McGregor's encounter with Mayweather a loss. He'd probably be significantly worse off than he is now had the fight never happened.
5. Artemij Sitenkov
When it comes to audience size and exposure, McGregor's loss to Lithuania's Artemij Sitenkov is on the extreme opposite end of the spectrum from his loss to Mayweather.
This defeat, which came by way of first-round kneebar, according to Sherdog, occurred in the Irishman's third professional fight, back in 2008. Most available footage of it looks like it was shot through the lid of a Pringles can—it's that bad.
It's because this loss occurred so early in McGregor's career that it appears so low on our list. Young fighters lose all the time, particularly when they're willing to take risks, as McGregor always has been.
Case in point: While the Irish star was just 2-0 at the time of the bout, Sitenkov was a significantly more experienced 5-4. It takes guts to accept a challenge like that so early in your career.
4. Joe Duffy
This loss, which came by way of arm-triangle choke under the Cage Warriors banner in 2010, also occurred early in McGregor's career in his sixth pro fight.
On the surface, it was a pretty tough L. Sherdog has the official end time as 0:38 of the first round. That being said, it's fairly excusable, not only because McGregor was still relatively new to the sport at the time, but because Joe Duffy turned out to be a pretty great fighter himself.
In fact, "Irish Joe" eventually earned a UFC contract of his own. While his UFC career ultimately flamed out with consecutive losses to James Vick, Marc Diakiese and Joel Alvarez, he did have some success in the Octagon, defeating the likes of Mitch Clarke and Reza Madadi, and even battling a fellow McGregor rival in Poirier.
There's really no shame in losing to a guy like Duffy in your sixth pro fight.
3. Khabib Nurmagomedov
Just like his loss to Mayweather, McGregor's loss to Nurmagomedov went down in front of a lot of people. In fact, it headlined the most successful pay-per-view in UFC history: UFC 229. That alone made it feel significant.
What really made this loss significant, however, was McGregor's ceaseless pre-fight trash talk. He talked the talk, but he failed to walk the walk. Instead, he was repeatedly taken down, controlled, and ultimately submitted with a fourth-round neck crank.
The reason this loss doesn't get the top spot on our list is that, like McGregor's loss to Mayweather, it was a fairly predictable outcome. Heading into the fight, Nurmagomedov had never been beaten before—and he'd made the vast majority of his wins look easy.
While many fans believed McGregor could be the man to end Nurmagomedov's unbeaten run, he ultimately went the way of the 28 other men who attempted to do so—and in hindsight, there's not a lot of shame in that.
The Irish star failed a task with a 0 percent success rate. You can't really fault the man for that.
2. Nate Diaz
This loss, which occurred at UFC 196 in 2016, is arguably the most famous of McGregor's career—and for good reason.
At the time, the Irishman was 7-0 in the UFC, with highlight-reel stoppages of world-class foes in Jose Aldo and Chad Mendes still visible in the rearview mirror. To say he had some wind in his sails would be an understatement.
He had originally been expected to challenge Rafael dos Anjos for the UFC lightweight title at UFC 196. When Dos Anjos was forced out of the fight with an injury, however, McGregor accepted a short-notice welterweight fight with Nate Diaz, who, at the time, was viewed as little more than an entertaining veteran—certainly not the kind of fighter who was likely to derail the Irishman's momentum.
Of course, that's ultimately what ended up happening.
After a strong first round, McGregor faded significantly in the second, and after absorbing some big punches on the feet, he shot for an ill-advised takedown on his submission-savvy rival. Moments later, he was tapping to a rear-naked choke.
It was a tough setback for McGregor for multiple reasons. It killed his momentum—instantly erasing the memory of his defeats of Aldo and Mendes. It came against a guy who had lost to vastly inferior fighters—a guy who happened to have accepted the fight on less than two weeks' notice. Perhaps worst of all, it gave the impression that the best way to beat McGregor is with a combination of cardio and grappling—a recipe that seemingly remains valid to this day.
1. Dustin Poirier
By the time McGregor stepped into the Octagon for his rematch with Poirier earlier this year, we knew he could be outgrappled. We knew that his deficit in the endurance department could be exposed. As such, it wouldn't have been particularly surprising to see him come up short via submission, or even to see him beaten by decision after five grueling rounds.
Yet neither of those things happened.
Instead, McGregor's lead calf was gradually chewed up by a procession of crippling Poirier kicks, and once it was adequately compromised, he was knocked out by a storm of second-round punches.
It was a shocking way to see him lose.
While his weaknesses were well known, he was still believed to have few equals in the striking department. Yet there he was, coming to in a dazed heap beneath the Jumbotron.
The Irishman was beaten at his own game. To make matters worse, he'd been undone by an attack as simple as the calf kick. While this maneuver is relatively new to MMA, it's become extremely popular over the last few years—to the point that anybody who pays even a modicum of attention to the sport is aware of its destructive, fight-changing power.
To see McGregor taken completely off guard by this attack indicated to many viewers that he'd lost his way in the gym—that he was sticking to his old tricks rather than learning anything new. In a sport that's evolving as rapidly as MMA, that kind of complacency can be disastrous.
Time will tell if McGregor has taken a more sagacious approach to training for his rapidly approaching rematch with Poirier—the man behind the worst loss of his career.