Joe Joyce's accurate punching caused Daniel Dubois' left eye to swell shut, and it was a simple jab in the 10th round Saturday that knocked him out.
Dubois was counted out after 36 seconds of Round 10. With the win, Joyce captured the vacant European, British, Commonwealth and WBC Silver heavyweight titles.
Dubois' vision was impaired for more than half the fight after his left eye was swollen shut by Joyce's consistent and patient work with his jab. The injury proved to be significant, and when Joyce landed one of his pinpoint left leads on the damaged eye in the 10th round, Dubois dropped to a knee.
Dubois was counted out while Joyce's celebrations were as calm as his boxing throughout at the Church House, a conference center not far from the Houses of Parliament and Big Ben in central London, England.
Joyce landed a large haul of titles with a win that also catapults him into world title contention next year. He is now among a short list of boxers likely to get a title shot if his English rivals Tyson Fury (WBC) and Anthony Joshua (WBA, IBF, WBO) meet for all the major world titles next year.
Dubois is such a heavy puncher that he is bound to play a major role in the heavyweight division over the next decade, but he will face criticism from some quarters in the way he surrendered his unbeaten record.
"He caught me with a good jab," Dubois said. "I couldn't see out of the eye. It just happens."
Despite being 12 years younger than Joyce (12-0, 11 KOs), and with nearly an identical professional record, Dubois (15-1, 14 KOs) started as the betting favorite with local bookmakers.
However, Joyce, whose amateur career included a silver medal at the 2016 Olympics, felt his experience would help him upset the odds and derail Dubois' impressive journey so far.
"I've felt power like that before, and with my experience I've learned to ride it and come back," Joyce said. "I felt his power, and I was happy to take it. I started to look at the eye, and I felt quite comfortable landing the jab. I tried not to get too close to him, too."
Dubois often starts fast, but this time he was contained and kept on the back foot by Joyce's accurate jab.
Joyce, who has sparred with both Joshua and Fury, was put under more pressure in the second, and Dubois unloaded a flurry of blows out of a clinch.
Dubois began to flow through the second round and made an aggressive start to the third round, catching Joyce a few times as he let his hands go.
Joyce's jab was less spectacular, but its accuracy left Dubois' face marked up and bleeding from the mouth at the end of the fourth round.
Dubois responded with a good fifth, landing a right hand straight through Joyce's guard in the final minute of the round.
The fight seemed even at the halfway point, but Dubois' corner had more cause for concern as the Greenwich boxer's left eye was closing with swelling.
Joyce had to deal with another attack early in the seventh, but his jab and work rate denied Dubois' any momentum.
Dubois' eye was completely shut when Joyce landed a jab flush on the damaged eye. After a delayed response, Dubois chose to take a knee and was counted out.
On the undercard, Jack Catterall (26-0, 13 KOs), from Chorley in northwest England and the No. 1 challenger for Jose Ramirez's WBO junior welterweight title, ended a year out of action by outpointing Abderrazak Houya (14-3, 2 KOs) by scores of 99-90.
Ramirez (WBC, WBO), of California, is expected to meet Josh Taylor (IBF, WBA), of Scotland, to decide the undisputed world junior welterweight champion in the first quarter of 2021 after Catterall made a deal to step aside to enable the champions to fight next.
"There's an agreement in place for me to fight the winner," Catterall said.
English super welterweight contender Hamzah Sheeraz (12-0, 11 KOs), 21, capped off an impressive display with a last round stoppage of Argentina-born, Spain-based Guido Nicolas Pitto (26-8-2, 8 KOs).
English boxers dominate the heavyweight division: Fury and Joshua hold all the world titles, and Dillian Whyte, Dubois and Joyce are among those hoping to get a world title shot in the next year or so.
David Adeleye, 24, from west London, is only at the start of his career, but he is showing real potential after registering a fourth professional win -- all by KO -- after a second-round stoppage of Danny Whitaker.