Floyd Mayweather saw off a hurricane in Las Vegas, a rough night to end a chaotic week. He was cut early and battered for several of the 12 rounds as Marcos Maidana rolled towards him with little regard for his own safety, but Mayweather did what he always does: he found a way to win.

His self-belief and his unbeaten record remain intact – he had the audacity to have notes bearing the statistic 46-0 scattered over the crowd before the first bell - and he has the Argentinian's WBA welterweight belt to add to the one he already looks after on behalf of the WBC. But the aura has diminished every so slightly, to the point where Amir Khan – who dropped and outpointed the former world champion Luis Collazo earlier in his welterweight debut and first fight at the MGM – is now a credible opponent. He ought to be, given he beat Maidana in 2010.

“A true champion can make adjustments,” Mayweather said, a hail of Latino boos drowning out his victory speech. “I got cracked early by a headbutt over my eye, and couldn’t see properly. If the fans want see it again, we can do it again.”

Maidana, clearly unimpressed, said: “Other fighters gave him too much respect and didn’t go toe-to-toe with him. I’ll give him a rematch because I won the fight. I’m not scared of him.”

Indeed, so rousing a performance did Maidana produce, a lot of fighters will now fancy their chances against Mayweather – and that makes any of his three remaining fights on his Showtime contract all the more intriguing. He is, at last, beatable.

The judges gave him a majority win by margins of 114-114, 117-111 and 116-112. I scored it for him 116-114, with the third and the eighth rounds shared, and the latter of those two could have gone to Mayweather.

It was always going to be a collision of the crude and the clever – but nobody outside Argentina could have predicted with confidence that Maidana would give the finest defensive boxer of modern times so much sustained hell.

Maidana and his shrewd trainer Robert Garcia made no secret of his fight plan beforehand: come out swinging that overhand right and hope to knock Mayweather out. Well, he tried. And he tried. Mayweather also promised an unreserved battle and, whether or not he really wanted to do that, he had little choice in a first round as tough as any he has endured in his career.

Showtime announced Maidana’s dressing-room weight as 165lbs, with Mayweather on the 148lbs welterweight limit, just as he had been at the weigh-in, which is extraordinary on both counts.

If Mayweather’s strategy was to start World War III – he was setting a record for blows to the back of the head after three rounds - Mayweather had said he welcomed an opponent bringing his best as it might force him to finally produce his A game, self-aggrandizement not that far from the truth; he had won all but a couple of his 45 previous bouts in cruise control. In the third, he got a 10-9 under his belt and was back in business.

In the fourth, Maidana still had not found his manners. He was warned for elbowing Mayweather, who now was complaining regularly, and he hit him low out of the referee’s line of vision. In between the argy-bargy, he landed enough decent shots to take the round and leave a cut above his rattled opponent’s right eye, a rare sight indeed.

Mayweather’s renowned defensive skills were under serious assault again in the fifth, and he was getting caught with crude punches that brought a steady roar from the packed arena’s loud Latino audience on Cinco de Mayo weekend.

Approaching the half-way stage, Mayweather knew he was in one of the toughest fights of his life, up there with those against Miguel Cotto and Jose Luis Castillo – and he found some championship form, whipping in left hooks and long rights that hurt and bamboozled Maidana.

The boxing lesson continued in the seventh, and those parts of the crowd rendered silent for the first part of the entertainment, encouraged their man with the familiar chants of “USA! USA!”. His confidence restored, Mayweather now looked like the master boxer who schooled Saul Alvarez and Robert Guerrero, dominant, sneering and utterly irresistible.

Maidana still had fire in his eyes, but blood around his left eye and maybe a doubt or two implanted at last in his mind. He bore in regardless and corralled Mayweather on the ropes, letting go a barrage of unpunished blows to the back of the head, and one below the belt. That apart, he earned a share of the points in the eighth.

Having earned Mayweather’s respect and full attention, Maidana now discovered what it was like to be on the end of what the great man described as his A game, which did not stop him going forward – and straight into a hail of sharp, hurtful blows to head and body.

The Maidana tank rumbled on in the 10th, and the sniper Mayweather received him with appreciation and interest, rattling his rock-like head time and again with jabs and hooks. He put a full stop to the session with a long right.

With six minutes left, Maidana surely knew he had to do what he said he would do at the start: knock Floyd Mayweather out. And, as everyone else has discovered, that is not only easier said that done, it requires taking awful risks. Tormented and angry, he barrelled Mayweather through the ropes, and gave him a whack in the ribs while he had his back turned and was trying to get to his feet.

Still chasing that knockout, Maidana landed a cracking right at the start of the 12th and Mayweather had to go into survival mode rather than the grandstand finish he most certainly wanted. Ducking, swaying and countering, he back-pedalled to the ropes, his familiar refuge, and retaliated when he saw the inevitable gaps. Both raised their arms, but the victory went the way most sane analysts thought it would.

Mayweather said Maidana was “a true champion, true competitor and a hell of a fighter”. He added, “He was rugged, a tough guy. Everybody used to seeing me dominate. People saying, ‘What’s wrong with Floyd?’ I think tonight we gave everybody the excitement they want. If he feels he won? September. He can get it again. Absolutely. I could have made the fight a lot easier if I wanted to. Did those rights hurt? He’s a strong fighter. I came in at 148, he came in at 165.”

He said he objected to the type of gloves Maidana wanted to use because he did not think they were safe. “When it’s all said and done, we already fought. But I’m in this to protect the boxers. A lot of them finish their careers without any money because they can’t articulate or even count anymore.

“I’m a mentally strong person, though. I’ve never done anything but box. That’s the difference between me and any other fighter – I can make adjustments.”

Referring to the one score of 114-114, he said, “I’m not going to complain about how the judges judge the fight. They’re not always right.”

He turned to Maidana and said, “You’re a great fighter, great champion. You have a beautiful family. But next time, don’t hit me in the dick.”

As for next time, Mayweather said, “I don’t know what I’m going to do for my next fight yet. But I always find a way to win. There’s no way to break the May-Vinci code.”

The night ended badly for some spectators. Advised that a crowd crush outside the press conference had injured several people, Richard Schaefer, the chief executive of Golden Boy Promotions, said: “If anything happened, the MGM will investigate, and their security. They are well equipped to handle big fights, so I am surprised to hear that.”

Guardian Service