Joe Joyce blocked Daniel Dubois in 10 rounds at Church Hut near Westminster Abbey to break the crown as the new heir to boxing became clear.
It marks the moment when Dubois proved that he was a heavyweight king in the waiting.
But Joyce tore up the script, ending Dubois’ unbeaten record and claiming his own world title.
Joyce did not appear to have been hit when Dubois fell to his knees on the 10th, and referee Ian John Lewis fired him.
It was the dramatic end of a fight that flowed with Dubois, who landed a heavy punch, but Joyce never gave up his job.
Dubois’ eye was closed by the end of the fight as a sign of Joyce’s accuracy.
Joyce was finally excited and made his trademark cart wheel to celebrate the biggest success of his professional career.
The blind mum mocked Marvel Dubois after seeing her son lose to her and telling her to avoid him.
Dubois’ success was unsettling, and Dubois was very keen to continue and continue his journey to the World Cup shot.
But the 23-year-old will have to rebuild his career after losing his lead pro in 16 fights.
The first round was KG, as the two fighters split in a draw to establish their job and joy.
In the second there was nothing to say about Dubois, who flew straight to Joyce and shook to the right before being followed by a strong left.
At the end of his job, Joyce tried to pull Dubois back, but Dubois went through another flood again.
At the end of the round, when the left-right combination landed on Joyce’s chin, Dubois won more than a third.
It was a tense match, and Joyce, with his trusty job, won the fourth again, and Dubois’ left eye began to swell.
Dubois’ punches got even stronger, hitting Joyce’s head back with a jab in the fifth.
Dubois coach Martin Bowers worked overtime between rounds to repair his man’s injuries.
Realizing he needed to step into the gas, Dubois started the seventh strong and shook Joyce back with another big right.
But the 2016 Olympic silver medalist faced the storm and continued to use his longevity to succeed with his job.
On the 10th came the moment of drama when Dubois fell to his knees on the canvas.
John Lewis knocked him out after 36 seconds.