The all-British heavyweight clash drew over 96,000 fans to Wembley, setting a new attendance record. Joshua's night started badly and got worse. In the first round, he got caught with a big shot while moving backwards with his chin exposed.
Things didn't improve for AJ in the next few rounds. He went down two more times and never really got back in the fight. By the fifth, Dubois kept throwing punches and landed the knockout blow, even though he took some heavy shots himself.
After the fight, Joshua watched the replay in his dressing room. Steve Bunce, who spoke to Joshua, told iFL TV:
"He's in a bleak place. He's in a horrible place and that's understandable but he did say to me 'I made a lot of mistakes'."
Bunce added:
"I understand he watched the fight back in his dressing room and he's a smart enough man, he'll be watching that and screaming what are your hands doing down there?"
Even before Joshua got hit, former heavyweight champ Lennox Lewis spotted trouble. He said to Bunce: "Buncey man, what's he doing with his chin? His chin is up there."
Joshua called this the toughest fight of his career. He might use his right to a rematch, but his path back to the top looks tough.
Dubois keeps his IBF belt and could face the winner of the Tyson Fury vs Oleksandr Usyk rematch in December. That fight will crown an undisputed champion, and Dubois might get a shot at all the belts.
The heavyweight division keeps moving. Joshua will need to regroup if he wants another crack at the title.