O’Leary vs. Chamberlain Predictions – Full Card Best Bets & Odds

• Pierce O’Leary defends the IBO light welterweight title against Mark Chamberlain
• Rising star Royce Barney-Smith features in the co-main event against veteran Reece Bellotti
• Check out the best analysis, predictions and bets for the full O’Leary vs. Chamberlain fight card below

---

Four months after winning the IBO light welterweight title by stopping Maxi Hughes, Pierce O’Leary (19-0) returns to defend the belt against English southpaw Mark Chamberlain (17-1-1).

O’Leary, 26, and Chamberlain, 27, headline a Queensberry Promotions fight card from the 3Arena in Dublin, Ireland. The event is scheduled to begin at 7 p.m. BST / 2 p.m. ET, with main event ring walks tentatively set for 10 p.m. BST / 5 p.m. ET.

A slew of European prospects compete on the undercard, including undefeated super featherweight Royston Barney-Smith (16-0), who takes on Reece Bellotti (20-7) in the co-main event. Barney-Smith and Bellotti will throw down for the vacant IBO inter-continental super featherweight title.

Pierce O’Leary vs. Mark Chamberlain Fight Card Odds

As the defending champion, O’Leary is the modest favorite to retain his title at -230, giving him an implied win probability of 69.7 percent. Chamberlain comes back at +190 to win his first world title.

Barney-Smith is tied with undefeated Irishman Steven Cairns as the biggest favorite on the card, both listed at -650. Cairns takes on 30-year-old Senan Kelly in the biggest fight of his career to date on the undercard.

Odds as of July 31, 2026, on FanDuel Sportsbook. Check out the best boxing apps in 2026 to place a wager.

Pierce O’Leary vs. Mark Chamberlain Prediction

On paper, Mark Chamberlain will be one inch taller than the IBO champion. However, Pierce O’Leary’s strength will make him seem like the much bigger fighter, which is a big factor given his physical, bully-like approach.

O’Leary might not be the most technical boxer, but he is all gas from the jump and brings the fight to his opponent from bell to bell. Chamberlain tends to be a slow starter and prefers to take his time warming up to his fights in the middle of the ring. That approach will give O’Leary every opportunity to create the grimy fight he wants, which he will happily take.

They call Pierce O'Leary the Big Bang for a reason 😅#OLearyChamberlain | August 1 | Live on DAZN 🤳 pic.twitter.com/q4dbBzxIJe

— DAZN Boxing (@DAZNBoxing) July 30, 2026

Once O’Leary takes the wheel, Chamberlain is not going to like where the fight goes from there. O’Leary is relentless, merciless and brutal once he even gains the slightest upper hand on his opponent. Chamberlain’s jab and footwork are not on par with where they should be to keep the fight at his range.

If the champion gets going, it could be a fairly convincing one-sided affair. Chamberlain does not take damage well and will have a supremely difficult time earning O’Leary’s respect if this becomes a war of attrition.

• Pierce O’Leary by KO/TKO (+260 on FanDuel)

Royston Barney-Smith vs. Reece Bellotti Best Bet

If Royston Barney-Smith can get past Reece Bellotti, he would put himself right on the doorstep of international superstardom. The 22-year-old will have all the advantages against Bellotti on paper — Barney-Smith is 13 years younger and the much longer, faster fighter — but he will need to be prepared to dig deep to remain undefeated.

From the outside, Barney-Smith is clearly the better boxer. His distance management is second to none, and he combines it with elite patience, timing, and defense that are well beyond his years. It will be up to Bellotti to close the distance and make this a grimy phone booth fight, which he has no problem doing. If Bellotti can force Barney-Smith to be uncomfortable in the trenches all night, he can wear on the younger fighter and pull off a sensational upset.

SUGAR BOY ROY! 😮‍💨🔥

Royston Barney-Smith stops Carlos Rayo with a vicious body shot 🥊#GilleyMcGann | #FightNight | LIVE on TNT Sports 3 and discovery+ pic.twitter.com/ZO6P6ZBDmx

— Boxing on TNT Sports (@boxingontnt) October 18, 2024

But for Bellotti, the issue is that he naturally prefers to box at range. Barney-Smith already has an elite jab, timing and vision, which he uses very well in the ring. Repeatedly closing the distance against the Englishman’s fast and deceptively powerful hands is much easier said than done. Bellotti will be playing with fire all night at the risk of running into Barney-Smith’s sharp right hand and uppercut.

Bellotti can be a difficult fighter to read due to his unorthodox approach, but despite being just 22, Barney-Smith is already adept at systematically breaking down his opponents piece by piece and absorbing every bit of information thrown his direction. The uphill battle for Bellotti is a bit too steep for him at this point in his career, and he will run into something that stops him dead in his tracks.

• Royston Barney-Smith by KO/TKO (+125 on FanDuel)

Gary Cully vs. Lee Reeves Prediction

The Irish Slenderman returns in Dublin on Saturday, with 6-foot-2 Gary Cully taking on Limerick-based southpaw Lee Reeves. As usual, Cully owns a decent height advantage over his opponent, which plays a part in him being the slight favorite.

Fans have already seen that Cully, who is 4-2 in his last six fights, is not a championship-level fighter. His lackluster fundamentals provide a clear ceiling for his career and prevent him from beating the best fighters in the world.

However, Cully is rightfully billed as the favorite against a regional boxer like Reeves. The 31-year-old former ‘Survivor’ contestant is used to being the bigger fighter in the ring, which he will clearly not have in his favor against Cully. Reeves is also a protected fighter with a manufactured record, having faced just five opponents with a winning record. Reeves’ last four opponents have a combined record of 6-26.

GARY CULLY IN HALF A MINUTE 😱#TaylorCarabajal pic.twitter.com/2kVeL5Rh14

— DAZN Boxing (@DAZNBoxing) October 29, 2022

Nothing about Reeves’ career to this point has prepared him to overcome the physical obstacles he will face against Cully. Reeves has a good jab and solid footwork, but it is nothing Cully has not seen before.

For the first time in his career, Reeves is facing a boxer who will not fold at the first sign of adversity. Cully is not the most confident bet on the card, but he is bigger, more experienced, and has beaten fighters better than Reeves before.

• Garry Cully (-140 on FanDuel)

Steven Cairns vs. Senan Kelly Best Bet

In his 13-fight professional career, Senan Kelly has only faced two fighters with more than 10 fights and a winning record, and he lost to one of them. He is now thrust into his biggest challenge by a mile against surging Irish star Steven Cairns.

Still just 21, Cairns entered the professional scene after amassing an impressive 101-9 amateur career. He represents that amateur pedigree in his fight style, which is built on his patience, strong jab and impeccable footwork.

But whenever anyone looks at Cairns, the biggest attribute that immediately shows up on paper is his power. ‘The Irish Takeover’ is one of the pound-for-pound most naturally powerful boxers in the game. He fights with that as his best strength and rarely forces the issue, trusting that his level-headed approach will get the job done.

A brutal 𝒃𝒐𝒅𝒚𝒔𝒉𝒐𝒕 & a 𝒃𝒂𝒄𝒌𝒇𝒍𝒊𝒑 🤯

There’s never a dull moment when Steven Cairns is in the ring 🙌#OLearyChamberlain | Saturday | @3arenadublin, Dublin | Live on @DAZNBoxing pic.twitter.com/Esl6MgK5Xh

— Queensberry Promotions (@Queensberry) July 29, 2026

Kelly is a fine test for Cairns at this point in his career, even if he is still likely to walk through it without breaking much of a sweat. There is nothing that Kelly does better than Cairns, who will be faster, stronger and much more powerful.

Kelly will at least be one of the first fighters to throw punches back at Cairns, but with a 17 percent knockout rate, there is little to no threat to dissuade the young wrecking ball. If anything, Kelly’s willingness to throw with Cairns will open up more opportunities for another big highlight. Cairns will be the first fighter to ignite the crowd at 3Arena on Saturday night with an emphatic victory that thrusts him up the rankings.

• Steven Cairns by KO/TKO (-160 on FanDuel)