Anthony Joshua suffered a shocking knockout loss to Daniel Dubois, his far less celebrated British rival, on an extraordinary night at Wembley Stadium. It was a crushing defeat for Joshua who was knocked down in the first round and then utterly dominated and sent repeatedly to the canvas. The brutal end was finally sealed in the fifth round when, just as Joshua tried to turn the tide of a one-sided beating, Dubois landed two shattering right hands which resulted in a conclusive stoppage.

Even though Dubois was the nominal IBF world heavyweight champion, he walked to the ring first in a clear sign that he was meant to play a supporting role to The Joshua Show in front of 96,000 fans. Dubois had never experienced such a searing atmosphere before but he looked composed and determined as he climbed through the ropes. But he had a long wait before his more exalted rival joined him.

Related: Daniel Dubois knocks out Anthony Joshua to retain IBF heavyweight championship – as it happened

A Joshua fight entrance is always overblown and makes some of us yearn for those long-lost nights when Mike Tyson, shirtless and in black trunks, walked menacingly and silently on his own to the ring. Dubois would soon replicate the bad intentions and percussive force that once personified Tyson.

At least Joshua looked concentrated but the laboured prelude dragged on through the anthems and ritual introductions. Dubois was booed while Joshua was cheered deliriously before, finally, they were alone in the ring. An astonishing fight was about to unfold.

Dubois was the early aggressor and he stalked Joshua. He looked confident and full of intent as he backed up Joshua. Dubois was warned for excessive use of his head but his fists presented the most serious danger. A huge overhand right nailed Joshua, dropping him heavily near the end of the first round.

The contest changed in that shattering moment as Joshua looked badly dazed, even though he was saved by the bell.

Joshua was reeling early in the second as his 27-year-old opponent pressured him with ferocious force. A worried and sickly expression was etched across Joshua’s face and he was again hurt by a right and a clubbing left. Dubois soon caught him again and an anxious hum spread through the stunned crowd.

As they came out for the third Joshua tried to change the pattern of the fight behind his jab. His supporters also attempted to rouse him after such a rocky opening but then Dubois landed another monstrous left hand. Joshua wobbled and tottered against the ropes. He again needed to be rescued by the bell.

Related: Daniel Dubois’ Wembley triumph over Anthony Joshua – in pictures

Joshua was dropped again early in the fourth round as a scything left sent him tumbling to the canvas. It seemed as if the referee was about to wave the fight over even though Joshua beat his chest in sad and lonely defiance.

They were allowed to continue and the slow, pitiless beating continued as Joshua absorbed yet more punishment.

The decisive round showed the courage of a former champion. Joshua rallied, briefly, and he hurt Dubois for the first time as he landed a jolting right which rocked the younger man. But facing that desperate burst of fire, Dubois responded with clinical authority. He landed successive heavy right hands that left Joshua a crumpled and broken figure on the canvas.

Despair for Joshua and his backers was swamped by elation for Dubois, who can finally claim that he became a world champion in the ring as he retained the IBF title which had been gifted to him three months ago with this stunning victory. The real king of the division remains Oleksandr Usyk who, four months ago, became the first undisputed world heavyweight champion since Lennox Lewis in 2000 when the Ukrainian left a riveting contest against Tyson Fury with the IBF, WBA, WBC and WBO belts.

But, in a typically shameless act of boxing chicanery, the IBF soon forced Usyk to relinquish its title because he was already contracted to fight Fury again in December and unable to box their mandatory contender first. The IBF handed its championship as a present to Dubois, whom Usyk defeated last August, and set up his first defence against Joshua.

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But Dubois deserves to savour the sweetness of his remarkable victory while, in contrast, the 34-year-old Joshua will be devastated. His admirable but flawed career is now much closer to ending after he was beaten so violently by a hungry fighter who is seven years younger than him.

Wembley had once belonged, in boxing terms, to Joshua, but this is a hard and unforgiving business. Dubois was simply too strong, too fresh and far too powerful for a lost and fallen champion.