The junior welterweight pair will headline at Dublin's 3Arena on August 1, Queensberry Promotions announced Tuesday.

Chamberlain (17-1-1, 12 KOs) previously withdrew from their original March 14 date, having suffered an infection which hospitalized the 27-year-old two weeks out. Now fully recovered and set to head back into training camp shortly, he'll look to seize the Irishman's standing after O'Leary stopped Maxi Hughes in five rounds that night.

O'Leary (19-0, 11 KOs) is The Ring's No. 10-rated junior welterweight, while Chamberlain hopes to prove his credentials in a weight class he's growing into, having lost there on debut against Josh Padley in September 2024.

Padley (18-1, 6 KOs) has parlayed that surprise 10-round points win on the Anthony Joshua-Daniel Dubois undercard into a short-notice world title shot at lightweight, before earning a promotional deal with Matchroom and success after moving down in weight.

He's now the European 130-pound beltholder and will make the first defense of that title against Aqib Fiaz on June 6. Chamberlain has only boxed twice since.

The Portsmouth puncher was held to a 12-round majority draw after a thrilling firefight with Jack Rafferty last August in Altrincham and ventures into another opponent's backyard this summer seeking a career-best scalp.

When their fight was first announced, Chamberlain expressed as much.

"I've got gloves," Chamberlain said. "I'll travel and I’ll fight anyone, anywhere. If it makes sense, then why not? All the pressure is on him, I've done it with going up to Manchester and into Jack Rafferty's back garden, so I'll do it again here."

O'Leary was predictably bullish about the assignment when talking to The Ring's John Evans in February.

"Who has he fought at 140?," O'Leary said. "Just Rafferty. Look, he got through it. It was a great fight, a great barnburner for both of them, but I'm no Rafferty, that's the difference. I'm looking forward to it, obviously the southpaw style is awkward, but we'll adapt quick. It's nothing I haven't seen."

O'Leary is the WBC's No. 5-rated contender for Dalton Smith's world title, while the 26-year-old Dubline resident sits at No. 12 with the WBO. Chamberlain is ranked No. 12 by the WBC, so this figures to be an eliminator of sorts between two fan favorites keen to level up as further world-level challenges and more lucrative opportunities await the victor.