In August 2017, the entire sporting world was transfixed on the cross-promotional fight between the two biggest stars in combat sports.

In a surreal moment, undefeated boxing champion Floyd Mayweather came out of retirement to welcome UFC champion Conor McGregor into his world inside the T-Mobile Arena in Las Vegas. It was truly a spectacle few could have imagined as they witnessed the greatest boxer of his generation square off against a brash mouthed Irishman with zero professional boxing fights.

So how did this fight even come about? Why would a a 40-year-old boxer, who hadn’t fought in two years, want to fight 30-year-old mixed martial arts champion in the prime of his career?

According McGregor’s head coach John Kavanagh, the process behind making the “money fight” wasn’t as challenging as it was made out.

“It was funny how it all came about,” said Kavanagh during an appearance on the Joe Rogan Experience. “Shortly after [McGregor’s win over Eddie Alvarez at UFC 205] we were at a function and I pulled Conor aside and shook his hand and said ‘Alright, you’re done. Enjoy the rest of your life.’ He was shocked I was saying this. But I said ‘What else are you going to do? You’re a two-weight champion, you’ve gone out the other end of this meat grinder with no damage. You’re in a very small percentage and you’ve made plenty of money. Go off and enjoy yourself.’

“Then a couple of months went past and the Mayweather fight started talking. I could understand because now his grandkids would be financially secure. So it made sense because it was a big payday. It didn’t make sense for any other reason. He enjoyed the competition side of it. No matter what you’re doing with Conor, it’s going to be a competition.

“So when him and Floyd started having a back-and-forth and goes ‘let’s go to boxing and be the best boxer in the world.’ For me, on the outside, it made sense to do. Nothing else was really make sense at the time. It was going to be damaging. Boxing is a horrendous sport to prepare for. We’re going to be looking at one thing, punches to the head. But it’s so damaging. The only justification I could see is his grandkids would be financially set.”

In the end, Mayweather walked through McGregor en route to a 10th-round TKO. While McGregor did find success in the early rounds, Mayweather’s experience and McGregor’s cardio proved to be his downfall.

For Kavanagh, he couldn’t help but admire their opponent’s masterful performance in the art of the sweet science.

“In that fight, it was just brilliant to watch Floyd and how he managed his energy,” said Kavanagh. “I think he threw one punch in round one and not much more in round two. It was such an amazing strategy. Then switching from the usual style of hands up and walking in. Conor did upload a lot on his forearms. It was very inefficient, which is the opposite of what I would describe Conor’s fighting style. This what a lot of punches. It was one of the few bits of advice I gave him in the corner that was of any use because I’m not a boxing guy.

“There was a reason [Floyd] isn’t throwing anything. This is 12-rounds. There’s almost like there’s three parts to a fight. There’s rounds one through four, then there’s five to eight and there’s nine to 12. Floyd just worked that beautifully. It’s something we’d do a lot more if we’re to ever get another boxing fight and just recognize that’s there’s 12 rounds and pace yourself. [Conor] was sort of in the MMA mode of just big shots and just light the guy up. But Floyd is the best at not being lit up.”

Even though Kavanagh’s star pupil failed in his attempt to become the first pugilist to figure out the Rubik’s Cube that is Mayweather, he felt McGregor fought brilliantly for a man making his professional debut at such a historic event.

“I knew no matter what happened, it was going to be a good fight,” said Kavanagh. “It wasn’t going in and you’re just like ‘Oh God, he looks terrible. He’s missing with every shot and he’s being made to look silly.’ It was a good fight. It was entertaining. No one in the crowd was saying it was ridiculous. No one was saying it was a waste of money. So it was an entertaining fight. It’s one of those things where I’ll be an older man and I’ll be talking about the time we went into the boxing world and fought Floyd.”

Looking back, Kavanagh smiles fondly on the journey he took with McGregor and the rest of his team. It was a moment in time few will forget let alone experience again. But for Kavanagh, he still can’t believe they actually went into battle against boxing royalty.

“Even on the night of the fight, I was scratching my head going ‘What am I doing here? That’s Floyd Mayweather and his dad over there,’” admitted Kavanagh. “Of all of the boxers, I always preferred watching Floyd over anyone else because I love defense. Defense to me is the most intriguing part. It’s beautiful It’s so interesting to watch because his whole career was defensive-based. He never really took the shot, never really was damaged in the gym, never was damaged in the fights.

“But yeah, when he was in the ring and we’re working in the corner, I’m just going ‘What the hell is Conor doing fighting Floyd Mayweather?’ It was just strange. Even in the beginning, I’m so used to Bruce Buffer, it was different guy and he hit the bell three times. I was like ‘Oh yeah, they do that in the Rocky movies. I remember that.’

“So right until the end, it was still head scratching. Even at then end, Floyd came up and gave his little compliment of ‘Oh he’s got a hell of a shot and he’s tough as nails.’ It was a great experience, I wouldn’t change any of it.”

Following the bout, rumors began to swirl of Mayweather donning a pair of MMA gloves and facing McGregor inside the UFC octagon. Inevitably, these talks turned out to be nothing more than pure speculation.

Well, according to Kavanagh, that may not actually be true as he revealed there were indeed talks of some sort of hybrid fight where takedowns and head kicks weren’t allowed. But McGregor wasn’t interested in the exhibition fight.

“There was talks of [a fight with only] leg kicks,” said Kavanagh. “I will say Conor absolutely doesn’t want to do that. He wants to fight UFC rules or boxing rules. There is zero interest in a hybrid fight… He shot it down straight away. He’d fight him obviously in MMA rules. But Floyd is an intelligent guy, he’s not going to do that. He’s no fool.”

As for McGregor’s fast rival — and former boxing sparring partner — Paulie Malignaggi, Kavanagh said a future boxing match between the two is not out of the question.

“It is absolutely not out of the realms of possibilities,” Kavanagh said. “There are all sorts of crazy rumors going around the management team and the fight team about what might happen next. It could be boxing, it could be him [Malignaggi], it could be Floyd. All sorts of names are being thrown about.”

Malignaggi left McGregor’s training camp for Mayweather last year quickly after multiple disputes about the leaking of sparring photos and footage. Kavanagh said fans might get a chance to see the whole second sparring sessions between McGregor and Malignaggi themselves soon — on Netflix.

“I think there is something being released on Netflix soon based around that fight and it’ll have all the rounds,” Kavanagh said. “We have the 12 rounds. As far as I’m aware, I just did an interview for it recently. I think it’s a three part documentary that’s going to be on Netflix soon. So people will get to make up their own minds about it.”

The rivalry between McGregor and Malignaggi won’t go away any time soon, Kavanagh believes.

“It turned out to be a great contest,” Kavanagh said of the sparring sessions between the two men. “And I’ll say contest because it wasn’t a spar, they were talking the whole time. They were talking the whole time, Paulie was talking to me, he was talking to the cameraman, he was almost better than Conor at it, it was great to watch. Everybody had a great night, and I think they both actually bizarrely enjoyed it. It’s like Conor and Nate (Diaz). It’s Batman and The Joker, they both need each other. They hate each other, but they love each other.”