Floyd Mayweather Jr., in a span of just a few seconds, did what he does best. First he put on a boxing clinic, scoring a 10th-round technical knockout over Conor McGregor in a highly-anticipated bout between the boxing superstar and mixed-martial arts champion. And then Mayweather jumped on the ropes, barking to the crowd and making sure everyone properly acknowledged what he’d just done.

The 40-year old undefeated fighter picked up his 50th career win, giving him one more than Rocky Marciano, the ring legend who retired with a 49-0 record.

The night’s biggest surprise wasn’t that Mayweather was the one lifting his hand in the end, but that the fight wasn’t the snoozefest many feared. McGregor was making his boxing debut but managed to take the fight to Mayweather early and absorb big punches late. It was a resounding loss for McGregor, the brash Irishman who predicted a second-round knockout, but not one that he’ll likely be embarrassed by.

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“He was a lot better than I thought he was,” Mayweather said, speaking perhaps for much of the boxing world. “He used different angles. He was tough competitor, but I was the better man tonight.”

“He was a lot better than I thought he was,” said Floyd Mayweather, above, who lifted his career mark to 50-0 with Saturday night’s TKO of Conor McGregor in Las Vegas. “He used different angles. He was tough competitor, but I was the better man tonight.” (Joe Camporeale/Usa Today Sports)

After months of hype and trash talk, when the gloves finally came on and the opening bell rung for what was billed as the most lucrative fight in combat sports history, Mayweather and McGregor promised to put on a show. To the surprise of many, they delivered.

As expected, McGregor was the aggressor early, taking the fight to Mayweather. He fired his fists like pistons, whereas the boxer seemed content to feel out his foe and wait for opportunities. Mayweather threw 28 punches total in the first three rounds, landing only 12.

“Our game plan was to take our time, go to him, let him shoot his shots early and then take him out down the stretch,” Mayweather said.

By the fourth round, it was clear that McGregor wasn’t looking for just one big knockout blow; he intended to box and was actually scoring, thanks in part to Mayweather’s lack of offense.

[Recapping Floyd Mayweather’s win, round-by-round; Main card results]

“He’s composed,” McGregor said. “He’s not that fast, he’s not that powerful, but, boy, is he composed in there.”

The crowd, announced at 14,623, was a partisan one, clearly in McGregor’s corner, and they were excited that for those first few rounds, McGregor showed that he would be no pushover, regardless of his ring experience. That’s part of the reason UFC President Dana White likes to call him “the unicorn.”

Floyd Mayweather will try to improve his record to 50-0 against Conor McGregor, who is fighting in his first professional boxing match. (Thomas Johnson,Dani Player/The Washington Post)

“He’s unlike any other fighter I’ve ever dealt with in my entire career,” White says. “His belief in himself is insane.”

While McGregor managed to stick to boxing rules, Mayweather complained some punches to the back of his head were illegal, and he gave McGregor a shove after the bell ended the fifth round.

In the middle rounds, Mayweather was still light on his feet and McGregor appeared to slow considerably. Not coincidentally, that’s when Mayweather started throwing — and landing — with a lot more ease. Suddenly, in the sixth round, the boxer was the one pushing McGregor around the ring and posting his biggest round of the night.

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While the bout felt close to even at the midway point, there was no turning back for Mayweather, and McGregor, who’d only fought beyond the second round in twice in 24 career MMA fights, simply didn’t have the legs. Mayweather started doing damage in the seventh, landing a couple of strong rights to McGregor’s face.

And then in the ninth, McGregor seemed to defend himself mostly with his chin, and Mayweather started putting on a show. One round later, Mayweather uncorked a straight right that sent McGregor backpedaling into the ropes. Mayweather pounced, unleashing a flurry of strong punches until referee Robert Byrd waved his hands and stopped the fight 1:05 into the round.

After his slow start, Mayweather landed 62 punches — including 59 power punches — in the final two rounds, compared with just 14 by McGregor. The Irish star said later that he was tired but not hurt.

“I get a little wobbly when I’m tired,” he said. “But get me in the corner and I’ll recover and I’ll come back. There’s a lot on the line here — he should have let me keep going until I hit the floor.”

The judges’ scorecards didn’t find the fight to be as close as many fans might have. One judge gave McGregor the first three rounds, but the other two gave Mayweather all but Round 1.

The fight itself served as a welcome exclamation point on a relentless promotional campaign. Spurned by some boxing enthusiasts and MMA devotees as shameful novelty, the fight quickly exploded into a pop culture event, pitting together a pair of brash, colorful characters who managed to transcend their respective sports.

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The fight was more than a year in the making, and in June the two sides agreed to terms, ensuring a life-changing payday for McGregor and one last boxing purse for Mayweather. Whenever everything is finally counted, reports suggest McGregor could ultimately pocket as much as $100 million and Mayweather could possibly earn double that.

The fight is expected to break many of the economic records set by Mayweather’s win over Manny Pacquiao in May 2015. Promoters were targeting as many as 5 million pay-per-view buys and said the bout would be viewed in more than 200 countries.

“I think we gave the fans what they wanted to see. I owed them for the Pacquiao fight,” Mayweather said. “I had to come straight ahead and give the fans a show. That’s what I gave them.”

Both fighters had financial incentive to promote the bout heavily and together they embarked on a four-city, three-country press tour, taunting each other in crass, vulgar terms in arenas packed with thousands of fans. The two traded insults, misogyny and racial-tinged lewdness, toeing the line of indecency and then obliterating it altogether.

They drew harsh criticism, but the buzz and anticipation for the fight only seemed to grow. Even though oddsmakers listed McGregor as a major underdog, many fans were struck by the oddity of the bout, curious how the biggest MMA star would fare against the best boxer of his generation.

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“The best fighting the best,” Mayweather said earlier in the week.

While the bout took place at 154 pounds, Mayweather weighed in at 149½ one day earlier and McGregor took the ring looking much closer to 170. Though he physically towered over the boxer, the UFC star was no match for Mayweather’s speed and stamina.

Even though McGregor earned more money in 10 rounds of boxing than he could ever hope to make in a UFC bout, he has told White that he wants to return to the octagon later this year. The MMA world can only hold its breath and see if McGregor still feels the need to rush back to the UFC after he cashes his boxing check.

Mayweather, meanwhile, showed that even at age 40, he’s still plenty capable of fighting. But reiterated after the bout that he’s done.

“This is my last fight, ladies and gentlemen,” he said to the crowd at T-Mobile Arena. “Tonight I chose the right dance partner to dance with. Conor McGregor, you’re a hell of a champion.”