Shaquille O'Neal's face said it all in a jaw-droppingly good fight between Tyson Fury and Deontay Wilder on the weekend.

The two heavyweights slugged out an instant classic that had boxing fans raving about a clash that will go down as one of the best in history — and NBA legend O'Neal was certainly impressed by what he saw.

One of a stack of celebrities in the Las Vegas crowd to witness the highly-anticipated trilogy fight, the basketball icon's reaction to a right hand from Fury midway through the fight summed up just how entertaining the show was.

A photo circulating on social media showed a wide-eyed O'Neal in awe of the action in the ring.

Fury and Wilder's first fight ended in a draw before Fury won the rematch via a seventh round TKO in February last year, and the Brit maintained his undefeated record by recovering from two knockdowns before flooring his American rival in the 11th round to retain his WBC crown.

"I know I'm the greatest heavyweight of my era, without doubt. Number one," Fury said following the epic battle at the T-Mobile Arena.

"I've fought the most devastating puncher in the history of our sport, not once, not twice, but three times."

Fury was initially reluctant on Saturday to rank his chances against past greats like Muhammad Ali or Joe Frazier, but later could not resist comparing himself favourably to the greatest heavyweights to have graced the division.

"There's been so many of them, so many great champions," he said. "Without sounding too clever, I place myself at the top of the pile. I believe I can beat any man in history, any man."

Sunday's thriller left many ringside observers struggling to think of a better heavyweight contest in boxing history.

"Listen, I've been in this business 57 years promoting fights and I truly have to say I have never seen a heavyweight fight as magnificent as this," said Fury's US promoter Bob Arum, who promoted 27 of Ali's fights including the 1975 classic "Thrilla in Manila" against Frazier.

Frank Warren, Fury's veteran English promoter, said the bout was "boxing history".

"It's the best live heavyweight fight I've seen," Warren said. "It was just amazing. Two warriors and just so absorbing. Tyson is the standout heavyweight of his generation.

"I have seen him box better. But the heart and the bravery he showed tonight were just amazing. Boxing should be proud of what he did tonight."

Fury, who now plans to take a break from the sport before contemplating a potential unification fight with WBA, IBF and WBO champion Oleksandr Usyk, or British rival Anthony Joshua, insisted he had never felt in danger against Wilder.

"He caught me twice. But I was never like thinking 'Uh oh, this is over'," Fury said. "I thought 'OK, good shot — but I will get you back in a minute', and I did.

"He shook me and he put me down, but that's boxing. And that's life as well — no matter how many times you get put down, it's all about getting back up."

Fury looked to have gained the upper hand after flooring Wilder in the third round, only for the 35-year-old from Alabama to respond with two knockdowns that had the English champion clinging on desperately in the fourth.

But it was the bigger, heavier Fury — landing the cleaner and more damaging blows — who finished the stronger, and the champion had Wilder down once again in the 10th with a right hook.

Wilder responded bravely to that knockdown by wobbling Fury in return. But the brutal energy-sapping nature of the fight, and Fury's relentless physicality, finally took its toll on Wilder in the 11th.

With the American exhausted and on the ropes, Fury landed the decisive combination. A right uppercut scrambled Wilder's senses before Fury crashed a right hook into his opponent's temple that sent the challenger tumbling to the canvas, barely conscious.

"Shots like that end careers," Fury said. "I just hope that he's OK. Because he took a lot of punishment tonight.

"Don't ever doubt me. When the chips are down I will always deliver.

"I give him the glory for the victory. He's a tough man — he took some big shots tonight.

"It was a great fight tonight as well as any trilogy in history."