A training partner of UFC welterweight champion Georges St-Pierre, Estima was situated cageside for UFC 158's main event. His presence, however, led to an unsavory exchange with Diaz, according to a post Estima later made to his Facebook account.
"After the fight, when I saw everyone hugging each other, everyone talking to each other, I thought as a sportsman it was my duty, as always we do, to send our respect, because both warriors there put so much time into it, and went there to do a big fight for the fans," Estima explained on Monday's edition of The MMA Hour. "Nick Diaz actually fought very good. I never met him before, ever in my life. It was the first time that I actually saw him. And I had shaken the cornerman's hands. When [Diaz] was coming in my direction, I stepped forward to shake his hand and he kind of pushed me to the side.
"I can't control that. I can only do my part. I can only go there and try to show my respect. He pushed me away. It's his way, what can I do? Afterwards Dana (White) even said to me, thanks for not pushing back. But even that, I [wouldn't] do that, to ruin the whole night -- a beautiful night it was for ‘GSP,' in his hometown -- everyone would be talking about that thing instead of the great victory that he had."
The feud between the two men traces back to May 2012, when Estima was scheduled to compete against Diaz in a charity BJJ superfight at the main event of the 2012 World Jiu-Jitsu Expo. Diaz infamously no-showed the match, which led to a bitter war of words between both sides.
Because of their well-documented history, in retrospect, Estima shouldered some of the blame for Saturday night's mix-up.
"At the time I was surprised and disappointed at myself, because I just thought to myself, ‘Why the hell did I even step forward with my hand?'" Estima admitted. "But at that mood, after the whole trash talking, I thought it was something like Chael Sonnen level. You know, talk, talk, talk, after that it's a fight, be professional afterward. I just felt like, I'm just going to send my respect, because I do respect him as a fighter. He's a great fighter. He's not there for trash talking. He's there for his achievements, and he proved that."
More upsetting for the 32-year-old was the fact that fellow BJJ standout Kron Gracie, with whom Estima has trained alongside and extensively competed against, thrust himself into the discussion by allegedly hurling insults and threats Estima's way.
Gracie helped prepare Diaz for his ill-fated BJJ superfight, and again trained with him in advance of St-Pierre. Although Estima once considered Gracie a friend, that no longer seems to be the case.
"Maybe [Kron] just wanted to show off," said Estima. "He knew that I wouldn't step forward. He's knows me, that I wouldn't step forward, so he just took advantage of it and just tried to look cool, and afterward go hang out with [Diaz]."
The alleged altercation, while minor, led Estima back to the subject of 2012's World Jiu-Jitsu Expo, where he hoped to snuff out any lingering resentment.
"I was very sad for what happened at the World Jiu-Jitsu Expo last year," Estima said. "Because after all the sacrifices that were made [for it] to happen, there was a lot of misunderstanding. I did get upset, and I said things that a lot of people misunderstand what I said, because I didn't mean that I wanted to challenge Nick Diaz to a MMA fight. Because that is not even a question, that he's a better MMA fighter than me. Not even a question about that. But what I meant was, I gave him the chance to fight me, me being one of the top guys in BJJ, ... to promote a good [cause] to the world, for the environment, and he dropped out. That was my issue.
"I [meant] that if it was the other way around, if he had been one of the top ones in MMA, if I had agreed to go and fight him, I would've backed it up. That's what meant. Not that I was challenging him, not that I wanted to f--king fight him in MMA.
"My English is not that good, and I just got away with the heat of the moment," Estima finished.
Regardless, Saturday's run-in was merely a small footnote to an otherwise successful weekend for the St-Pierre camp. Estima has already put the altercation behind him, even going out of his way to compliment Diaz's performance.
But above all else, the Brazilian is extraordinarily proud of St-Pierre latest accomplishment.
"He dealt well with the unexpected," Estima said of his training partner. "Which was good from my point of view. We had a great plan. I think 'GSP,' he was very excited in the first and second round -- push the fight, try to ignore Nick a little bit.
"And then Nick was very clever in the beginning because he wasn't expending any energy on this position -- turning the back, blocking 'GSP's' wrists and then trying to roll him over. He did a very job. He put [himself] in a situation where he was kind of safe, saving energy, when 'GSP' was expending a lot of energy.
"[St-Pierre] kept dealing with the kneebars and confronted the guys hips all the time, which make him always safe," Estima continued. "He managed to jab out well the distance from Diaz, because the idea was not being in boxing range. He wanted to be either in Thai boxing range or grappling range with Diaz. He managed to do pretty good other than the third round.
"Overall I think his performance was amazing. It was impeccable. He won all the rounds in my opinion, and he controlled the fight well. He used his whole [range of skills] to his benefit and I'm very proud of being part of this camp and helping him out."