Fighting in-front of a heavily pro O'Leary crowd, the 27-year-old southpaw got off to a tremendous start. He knocked down the hometown favorite, broke his nose in round two and put him over again with a well-timed uppercut in the third.

Badly damaged but still determined, the brave O'Leary dragged himself back into the fight and dropped Chamberlain with a heavy body shot in the seventh. With the fight in danger of slipping away, Chamberlain regathered himself to produce a stunningly accurate finish deep in the 10th.

Chamberlain (18-1-1, 13 KOs) told DAZN post-fight while he accepted being in for a brutal night's work when signing the contract, the realisation only dawned on O'Leary (19-1, 11 KOs) once he was in trouble.

"I've been saying all week he's been underestimating me and he clearly was," he said.

"First, second or third round, I caught him and actually heard his nose snap and that was it. He went down once, was down again later and I think it was real then to him, 'Oh, I'm in a fight'.

"I think he thought he was going to come and roll me over. He did put me down with a body shot that caught me and it took my breath away. That's why I took a knee."

Chamberlain isn't the type to shout, nor make promises about his intentions before a fight. Publicly, he accepted his role as the promotion's B-side but privately was intent on tearing up the script.

Nothing he encountered during a busy week of media surprised or knocked him off stride, allowing him to walk out into a cauldron-like atmosphere focused entirely on the task ahead.

"From when I got here on Wednesday, I've had it all week. 'The Pierce O'Leary Show' if you want to call it that," he said.

"We're in Dublin, his hometown. I'm going to bring my handful of people over and he's going to have his whole city behind him. I knew what I was signing myself up for when I got offered the fight and I love it, because all the pressure's on him, not me. I've come up with my gloves in my suitcase and am now the IBO champion."

Afterwards - as is common practice these days - talk immediately turned to a potential rematch. Chamberlain has made it clear that provided the money is right, he will fight anybody, anywhere.

Having travelled north to box Jack Rafferty last August before crossing the Irish Sea to take on O'Leary, he would like any return to take place closer to his Portsmouth home.

"Frank said in there [the ring] there's a rematch. No problem but he's going to have to dig deep in his pockets and I want it on my terms at home," he said.

"So, providing Frank's willing to do that for me I'm sure we can make it happen."