British heavyweight Dave Allen scored the biggest win of his career as a superb body shot stunned Australia's Lucas Browne at London's O2 Arena.
Allen, 27, has become a cult figure for boxing fans in recent years due to the openness with which he has highlighted struggles in and out of the ring.
He took shots for two rounds before a left to the body ensured a 10 count.
Fellow British heavyweight Dereck Chisora scored a workmanlike points win over the unambitious Senad Gashi.
Chisora, 35, faced an opponent who looked to move repeatedly and punch infrequently, resulting in a 100-90 100-91 99-91 points win for the Briton.
In defeat to Dillian Whyte last time out and in his outstanding win over Carlos Takam in July, Chisora fought up close, trading powerful hook shots frequently.
But in his first bout under new trainer Dave Coldwell - who guided Tony Bellew to a world cruiserweight title - Chisora was barely allowed to get close due to Gashi's largely negative tactics.
The bell was greeted by relative silence, as Chisora landed a 100-90 100-91 99-91 points win to extend his record to 30 wins and nine defeats, while Algeria-born German Gashi lost for the third time in his 20-fight career.
'There's only one David Allen'
The O2 Arena sang Allen's name following a win over a man who held a version of the WBA world title in 2016 and who had only previously lost to Whyte.
Allen, a former gambling addict who once fought Luis Ortiz at short notice because he needed money, has become a fan favourite, admitting he dislikes training and struggles with maintaining any form of diet.
Less than two years ago, he lost a Commonwealth title fight to Lenroy Thomas on a night when he opted to box in trainers - much to the frustration of promoter Eddie Hearn - and after which his own father told him sections of the crowd were laughing at him.
The Yorkshire fighter has since trimmed weight and trained with noteworthy focus, resulting in three consecutive wins which paved the way to a headline slot.
Early on against 40-year-old Browne, he came under fire, eating uppercuts at will.
But in the third round he slipped to his left before driving home a crushing body shot and celebrating wildly.
"Main eventing is one thing, but I had to win," said Allen. "It's alright telling my grandkids I headlined the O2 but I want more now. I've proven I can punch at a high level. It's a very good win.
"The left to the body was beautiful. Today I was fit. I could have done 12 rounds easily. He has underrated skill. It's a case of getting them down to my pace. I'm unbeatable at a snail's pace."
Elsewhere on the bill, Wales' Joe Cordina stopped Andy Townend to capture the vacant British lightweight title, while his fellow Rio 2016 Olympian Josh Kelly fought for the first time in five months and floored Poland's Przemyslaw Runowski several times on his way to a points win, extending his record to nine wins from as many bouts.