Mark Chamberlain stunned the Dublin crowd, landing a knockout in the 10th round to capture the IBO light‑welterweight belt. He returned to winning ways after a 2024 loss to Josh Padley, now standing at 18 wins with one defeat.

In the opening round, Chamberlain landed a flush left that sent O'Leary flying back onto the canvas. A second‑round left hook repeated the knockdown, putting the Irishman on the ropes.

O'Leary rebounded, striking a powerful body shot in the 7th round that forced Chamberlain to climb off the canvas. The British fighter survived the count and avoided major damage before the bell.

The decisive moment came in the final round: Chamberlain unleashed a combination, including a straight right, that dropped O'Leary and secured the stoppage, cementing his place in the division.