Dubois retained the IBF heavyweight world title but it was a stunning upset as he took apart the acclaimed former two-time world heavyweight champion.
A monstrous right hand to the chin dropped Joshua heavily in the first round.
In the second, Dubois swarmed all over him and Joshua was shipping severe shots.
Joshua was saved by the bell at the end of the third round.
A massive left hook had sent him tottering into the ropes, stunning him, and Dubois then unleashed a ferocious onslaught, hammering him down to the canvas again.
He made it upright on the bell to end the round and passed a close examination from referee Marcus McDonnell.
But a Dubois left hook tipped him over at the start of the fourth round. Joshua lost his footing afterwards which was not ruled a knockdown but he was in desperate danger.
Dubois’ left hook continued to find Joshua, but remarkably the former champion steered himself through the rest of the round.
After such a frenetic start there were hints that Dubois was starting to tire.
His output became a touch less ferocious. Joshua sensed something. He roared back at Dubois for a moment in the fifth round and slammed a right in. He sent another over, a full-power right cross streaking at Dubois.
He felt it but threw it back. Joshua shrugged off that punch with half a smile and unleashed another attack. Just for an instant it looked like Joshua, with his strength, could turn the tables.
But with Dubois retreating to his corner, and Joshua stepping to him, Dubois lashed a right down into his chin.
It spun him away, crumpling Joshua headlong onto the canvas.
There was no recovery from that, although Joshua tried. He attempted to heave himself upright, but the ending was utterly decisive. It was over.
Wembley Stadium, the scene of Joshua’s greatest triumph when he beat Wladimir Klitschko long ago now in 2017, had become the scene of his most devastating defeat.
Meanwhile, In front of a record crowd at Wembley Stadium, the occasion was spectacular.
For Joshua winning Dubois’ IBF title would have made him a three-time heavyweight world champion. It would also no doubt have put him in prime position to take on the winner of December’s Oleksandr Usyk-Tyson Fury rematch for the undisputed championship.
That has all been ripped away.
Instead, Dubois, an unlikely heavyweight star, has seized that place.
Dubois will be hugely gratified to have stamped his mark on the division. Questions have haunted him since his defeat to Joe Joyce almost four years ago.
A fractured eye socket saw him take a knee and the referee’s full count then.
He continued to test himself and took the ultimate challenge against unified champion Usyk in Poland last year. Usyk halted him too but Dubois has bounced back, building confidence in his victories over Jarrell Miller and Filip Hrgovic.
In the process, he picked up the IBF’s interim belt and saw that upgraded to the full world title when Usyk’s commitment to the Fury rematch meant he could not make a mandatory defence.
But this victory will take him to a whole other level, smashing through a British boxing superstar at Wembley Stadium is an astonishing accomplishment.
“I’ve only got a few words to say: Are you not entertained?” Dubois exulted afterwards.
“It’s been a long journey, I’m grateful to be in this position.
“I’m a gladiator, I’m a warrior to the bitter end. I want to reach the top level of this game and reach my full potential.
“I’ve been on a rollercoaster ride. This is my time, this is my redemption story, and I’m not going to stop until I reach my full potential.”
Admirably Joshua took the microphone in the immediate aftermath of that crushing defeat.
“Credit to him and his team. We rolled the dice of success, but we came up short,” he said.
“You know I’m ready to kick off in the ring, but I’m going to keep my cool, keep very professional, and give respect to my opponent.
“I had a sharp opponent, a fast opponent and a lot of mistakes from my end, but that’s the game.
“I’m always saying to myself I’m a fighter for life… We keep rolling the dice.”
Some of boxing’s biggest stars were in attendance, Tyson Fury and Oleksandr Usyk watching out for a potential rival, Roberto Duran and Terence Crawford taking ringside seats, Rory McIlroy, Conor McGregor, and figures from other sports as well as celebrities from the world of entertainment, not least with Oasis superstar Liam Gallagher performing three songs before the main event to add to the sense of occasion.
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