Cheavon Clarke stopped former world cruiserweight champion Chris Billam-Smith in Round 7 to announce himself as a serious contender on Saturday.
Clarke (13-2, 10 KOs), 35, dealt Billam-Smith's career a big blow when he dropped him twice before the referee stopped the non-title bout at the Copper Box Arena in London.
Billam-Smith (22-3, 14 KOs), 36, from Bournemouth, was expected to win the fight and put himself in contention for a fight against Jai Opetataia next year. But that fight, and any world title shot, is now in doubt for the former WBO world cruiserweight champion who was left on wobbly legs by Clarke's power punches in Round 7.
Jamaica-born, British-based Clarke is not even ranked in the top 10 by any of the world governing bodies but his career prospects look a lot better after pulling off a big upset win over Billam-Smith.
"Chris hasn't changed, feet is where I beat him," Clarke said in the ring. "He doesn't know how to use his feet. It's not about having his number, it's about doing your homework.
"But I don't have no beef with Chris. He's been a world champion, so give him his credit."
It was Billam-Smith's second defeat in four fights, after losing to Gilberto RamÃrez in a title unification fight two years ago.
Clarke, 35, who beat Billam-Smith when they were amateurs 10 years ago, landed the best shots amid a lot of holding in Round 1 when he caught Billam-Smith with some right hooks.
Billam-Smith struggled to get into any sort of rhythm in the early rounds and was then nailed by a big overhand right in Round 5. Billam-Smith was glad to hear the bell in the fifth as he sat on the ropes with Clarke unloading solid punches.
The signs were there that Clarke could threaten and in Round 7 he caught Billam-Smith with a right to the temple as his opponent leaned in following a punch. Billam-Smith slumped to the canvas and, after a count, Clarke unloaded a series of punches to send him sliding across the ropes and back to the canvas.
Billam-Smith was on wobbly legs after the second knockdown and when Clarke started connecting with more punches, referee Lee Every was correct in stopping the fight.
"I made a mistake, but I felt like I was winning the fight," Billam-Smith said.
Denzel Bentley, who briefly reigned as WBO middleweight champion earlier this year, unanimously out-pointed Shane Mosley Jr. by scores of 96-94, 96-95, 96-93 in a 10-round, non-title middleweight bout.
Bentley (24-3-1, 18 KOs), 31, from Wandsworth in London, got elevated from WBO interim champion to full champion earlier this year, but never made a defence and was stripped of the title last month after refusing to face mandatory challenger Yoenli Hernández.
This win at least keeps him in contention for big fights, even if he is not a world champion.
Mosley Jr. (23-6, 15 KOs), 35, from Las Vegas, son of three-weight world champion "Sugar" Shane Mosley, was busy in the first and second rounds on the front foot.
But Bentley seized on an opening in the second round to thread a right hand through Mosley's guard and onto his chin, which left the American on shaky legs. Bentley followed up with another stiff right to send Mosley down for a count.
It was the first time Mosley had been sent to the canvas in his professional career but he recovered well and was grateful that Bentley failed to deliver a threatening follow up.
There were other moments when Bentley again did not step on it after landing some punches and Mosley's workrate kept it a close fight.