Lawrence Okolie claimed the biggest win of his short career with a unanimous points victory over Isaac Chamberlain at London's O2 Arena.
The British cruiserweights shared a heated rivalry in recent weeks as they prepared to risk undefeated records.
Olympian Okolie, 25, dominated physically and knocked Chamberlain, 23, down in rounds one and six.
The judges scored an untidy bout 98-89, 96-90, 97-89 for Okolie, who took his record to eight wins from eight fights.
Chamberlain last week paid for an advert in Okolie's local paper, the Hackney Gazette, marketing his rival for work, while Chamberlain's trainer threatened to quit the sport if his man was beaten.
But Okolie followed a solid jab with a right hand which floored Chamberlain in the opening exchanges, although contact was minimal.
Chamberlain had a point deducted for holding in the second round, and referee Steve Gray later warned both fighters for the grappling which marred the bout as a spectacle.
IBF and WBA world heavyweight world champion Anthony Joshua, who manages Okolie, was ringside and said the bout "lacked finesse".
In the sixth round Okolie countered a left hand with a well-timed right to the side of the head, forcing Chamberlain to touch down with his right glove.
"Isaac is a good fighter and tested me in a different way," said Okolie. "It's good as a benchmark. I have nothing but respect for him for his mental fortitude.
"I said in the build-up that he would find it hard to work up close with someone as strong as me."
'Nothing can stop him' - Buatsi eases to win
Joshua Buatsi - Okolie's team-mate at the Rio 2016 Olympics - took less than two rounds to land a fourth professional win as a straight right hand wobbled fellow Briton Jordan Joseph, allowing Buatsi to smother his opponent before the referee stepped in.
"There's a crowd here, a nervous energy for me, so people I wanted to entertain," said 24-year-old light-heavyweight Buatsi.
"It's been a while since I last fought, I had a few minor injuries but this fight showed that both my hands are now OK."
Promoter Eddie Hearn said: "If he doesn't become a world champion we have failed or someone has failed. He will light up this arena for many years to come. Nothing can stop him. He has it all."
Britain's Ted Cheeseman, 22, scored a wide unanimous points win over experienced 31-year-old American Carson Jones at light-middleweight.