"It hurt to watch," Mendes admitted Tuesday on The MMA Hour.
"It's something I still think about. Sometimes (I) lay in bed still thinking about it. It's definitely going to take some time to get over it, but you know, that's just part of the game."
Mendes ventured into the shamrock whirlwind on less than two weeks' notice to challenge McGregor for the UFC interim featherweight strap on July 11, and though Mendes controlled the early stages of the fight, McGregor's promise of a second-round knockout ultimately proved prophetic. The Irishman chiseled away at Mendes' gas tank until drowning the weary American under a salvo of punches in the closing moments of the second stanza to seize gold.
While the loss was painful in and of itself, the thing that irks Mendes the most is that he was winning the fight right up until the moment he gave it away. And if he could do it all over again with a full camp to prepare for five rounds, he's confident the outcome would be different.
"110-percent, no doubt in my mind," Mendes said. "I'm not making excuses. I'm not sitting here saying that's the reason why I lost. But I feel that if I am completely prepared for that fight, I win that fight. Every single time."
The experience was a wild one for Mendes (17-3), and even two past title shots against Jose Aldo couldn't have prepared him for the spectacle that McGregor brings. A seemingly endless barrage of Irish fans invaded Las Vegas for the entirety of fight week, breaking records and giving the event a big show feel that's often missing from UFC pay-per-views.
Mendes and McGregor trash-talked each other all throughout the proceedings, and come fight night, Mendes looked to make good on his word. He owned the first round, scoring three big takedowns and blasting McGregor with hard elbows from top position, then appeared to be well on his way to repeating the feat in the second before his cardio failed him and the accumulation of McGregor's precise strikes became too much.
"His only way of beating me was tagging me on the feet," Mendes said. "And you know, he does a really good job of being in your face. He has that, like, Diaz style of punching. But anyone who can move around and stay light on their feet and take this dude down wins that fight every single time. I just, after scrambling around, and fighting for the amount of time that I did, I just wasn't able to get back to my feet and be light on my feet.
"I was stuck, and that's when he was able to tee off and that's why I lost. So I truly believe that if I was able to keep that bounce in my step and move my feet, keep that footwork going, that I wouldn't have been tagged and the round would've ended. We would've gone back and round three would've been just like round two. So it sucks. I think that's the hardest part, because I know I can beat this guy, and I was so close."
Mendes points to one sequence, in particular, that turned the tide of the match. After controlling a majority of the second round from top position, Mendes looked to pass McGregor's guard and lock up a fight-ending mounted guillotine. For a moment he appeared to nearly have it, but McGregor deftly squirmed out and retook his feet with a minute to go. The exchange left Mendes winded, and a few more hard shots from McGregor were all it took to signal the beginning of the end.
"I remember in that situation just feeling like, alright, I have complete control here," Mendes reflected. "He didn't feel like he had anything off his back. He wasn't trying to stand up. He was keeping closed guard. He didn't feel very strong or very controlling off the bottom, so I figured I'm going to pass guard and I feel like I could probably submit this dude. Watching past fights, seeing his losses, we knew that was something that was very possible.
"That's one of the things that upsets me the most. If I would've just stayed there and kept solid position, stayed in guard and just kept landing elbows, the round would've ended, I would've stayed on top. But I mean, that's the sport. We takes risks. We get in there and we fight another human being. And that was a risk that I took. I tried to finish the fight, and he scrambled and he was able to get back to his feet."
The loss served as one more instance of what is becoming a familiar refrain for Mendes. Much like his Team Alpha Male mentor Urijah Faber, Mendes is now 0-3 in UFC title opportunities, and he could be stuck in no-man's zone for the immediate future with losses to both the interim champion and reigning titleholder.
Still, the experience was unquestionably the biggest payday of Mendes' career, and an unexpected one at that. It didn't hurt Mendes' stock much either, as he's still the No. 3 ranked featherweight in the UFC's media-generated rankings. So while there were plenty of negatives to come out of the situation, there were more than a few positives as well.
"It's a loss. I got the big ‘L'. It sucks. But it was two weeks of craziness," Mendes said. "The whole Aaron Lewis thing, just being able to walk out to him singing my walkout song, looking back at him as I'm walking out and just seeing the crazy, crazy Irish fans. At the time, it's overwhelming. I had Irish guys talking crap to me in the hallways and stuff, walking to and from workout rooms back to my hotel. Just to see the amount of passion and support these guys have for our fellow athletes is crazy.
"Their countrymen, they just back them up so much. I honestly wish that we had that more in America. It's something that, it's just crazy to see, you know? The same thing with Brazil. When we went to Brazil and fought a Brazilian there, it was crazy how much the entire country has their athletes' back. That's something I'll something I'll never forget. Getting in there on short notice, the biggest fight of my career, against a guy who is going to be in the sport for a long time, it's just something that I'll never forget."