Much of the pre-fight buildup centered around O’Leary’s first headline appearance at the famous venue and his emergence as a hometown hero. Widely written off as a bit part player in the rising Irishman’s story, Chamberlain (18-1-1, 13 KOs) served a thrilling reminder as to why he was once a regular on Riyadh Season super cards.

The 27-year-old southpaw from Portsmouth dropped O’Leary (19-1, 11 KOs) once apiece in the second and third rounds, but he also had to pick himself up from an energy-sapping body shot in the seventh round. He recovered, composed himself and landed a stunningly accurate finish to stop the hard charging Dubliner at 1:37 of the 10th round.

Referee Leszek Jankowiak immediately halted the action when O’Leary fell forward to the canvas.

This was the best career win for Chamberlain, who enjoyed a sensational rise and performed on a series of Riyadh Season cards. He was unfairly written off after disappointing loss to Josh Padley in September 2024.

Chamberlain went away, rebuilt and looks well settled at 140 pounds. He proved that he is much more than a puncher when he stood up to everything Jack Rafferty could throw at him during an exciting draw 12 months ago and has now earned himself a route back to the very top.

Completely unfazed by a loud, partisan atmosphere, Chamberlain calmly boxed his way through the first round without any signs of alarm. He found the mark with a handful of long, left hands and controlled the hard-charging O’Leary with a pawing jab and some smart footwork.

O’Leary upped the tempo in the second, but walked himself into trouble. Chamberlain absorbed a couple of attacks, but he found the left hand time and time again and dropped O’Leary with a shot as their legs got tangled. O’Leary looked shocked and got up with blood pouring from a badly damaged nose.

O’Leary answered the bell for the third, but found himself pinned at arm’s length and directly in the danger zone. Most worryingly, he seemed clueless as to how to escape it. Chamberlain refused to get carried away by his success and dropped him again with a beautifully picked uppercut.

Roared on by the crowd, O’Leary rallied in the fourth. Crucially, he managed to avoid any more damaging shots and applied pressure from bell to bell. Chamberlain was never hurt, though he did begin to look disorganized and he found it much harder to find the target. He ended the round with blood coming from his own mouth.

Chamberlain boxed nicely in the sixth, but O’Leary seemed to have closed the gap on the scorecards and regained his confidence. He was able to initiate a couple of exchanges and his short, chopping right landed, but Chamberlain reasserted his dominance with a nice right hook of his own and a hard straight left.

Struggling through the seventh, the fight looked to be slipping away from O’Leary. He spat blood from his broken nose, but he suddenly loaded up, missed a wide left hook before he cleverly switched his attack to the body and Chamberlain sank to his knee from a hard right hand to the solar plexus. For a moment it looked like he might not beat the count, but he clambered up and survived the round.

Chamberlain regained his composure and boxed his way through the eighth, but O’Leary closed the gap on the scorecards and suddenly looked like the man in the ascendency. Chamberlain looked exhausted, but there was another twist to come.

As O’Leary pressed forward in the 10th, Chamberlain threaded a perfect left through his guard. Badly hurt, O’Leary froze and Chamberlain seized the moment. He produced a tremendous follow-up attack and Jankowiak stepped in to stop the fight as O’Leary fell forward.