Pierce O’Leary vs Mark Chamberlain Set for August 1 at Dublin’s 3Arena

Pierce O’Leary is heading back to the 3Arena this summer—and this time he’s coming as a world champion.

The unbeaten Dubliner will defend his IBO super lightweight title against Mark Chamberlain on Saturday, August 1, with the fight set to be shown live on DAZN. It’s a matchup that was supposed to happen earlier in the year before illness forced Chamberlain out, but it hasn’t lost any of its intrigue in the meantime.

O’Leary (19-0, 11 KOs) made the most of that setback back in March. Instead of Chamberlain, he faced Maxi Hughes and delivered a statement performance, stopping the experienced Brit in five rounds to claim the IBO belt. That night also marked his long-awaited homecoming, and the demand was clear—tickets were gone well before fight night, with the 3Arena packed out for his first pro appearance in Dublin.

Now 26, O’Leary returns as the main attraction once again, and the expectation is even bigger this time around.

Chamberlain (17-1-1, 12 KOs), a southpaw from Waterlooville, steps up for his second outing at super lightweight after building his reputation down at lightweight, where he picked up WBC Silver, WBA Intercontinental and IBF European honours. His move up in weight has already brought him into tough company—most notably a hard-fought draw with the unbeaten Jack Rafferty over 12 rounds in a British and Commonwealth title clash earlier this year.

That result left unfinished business of its own, but Chamberlain now turns his focus to Dublin and a shot at O’Leary’s world title.

With both men known for their willingness to engage and their punching power, this one has all the makings of a lively contest. It’s also a chance to see just how far O’Leary has come since his breakout night in March—and whether Chamberlain can spoil the party on Irish soil.

The card, titled “No Turning Back,” leans into the idea that neither fighter is likely to take a step back when the bell goes. Given what both have shown so far, that feels like a fair warning.