In winning their Pool B opener 82-8 against Romania, Ireland became the first team to score over 80 points in a Rugby World Cup match since Wales did so against Namibia back in 2011.

It was Ireland’s largest ever World Cup victory and the most points, tries (12), metres made (1091) and offloads (27) they have amassed in a match in the tournament’s history.

Captain Jonathan Sexton, who claimed a handful of records himself on the day, and Jack Crowley tallied up 11 conversions between them, setting a new Irish record in Test rugby.

However, there was some frustration with defensive lapses and attacks that broke down, especially off their usually reliable lineout platform. O’Mahony expects to see a return to form in that area this weekend.

“I think the main thing is to improve, get better,” he said, when asked about the team’s goals for round two. “There was plenty of stuff we were obviously happy with last week, but there was probably more that we weren’t happy with.

“Discipline certainly, penalties given away. We had Romania under pressure at times, but let them out easily with some quite silly discipline.

“I think some of our accuracy wasn’t where it could have been at times. Some fairly basic errors from ourselves that we would have expected much higher standards from.

“Set-piece wise, I think some of the moments where we got into their 22 where our lineout didn’t function. So, as I said, we’ve plenty of areas to improve on this week.”

Having ended last season with Six Nations and United Rugby Championship medals in his back pocket, O’Mahony has come into his third World Cup campaign in fine fettle despite missing some pre-season windows through injury.

The Romania game saw him score his fourth and fifth Test tries, adding to previous efforts against Samoa (2013), Russia (2019) and Italy (2022), as he made his first international start at openside flanker since the December 2020 win over Scotland.

In addition to his two tries and usual solidity in defence against the Oaks, the Corkman made a line break and more passes (13) than any other forward – during the World Cup’s opening round – except Italy’s Michele Lamaro (14).

Backing up for the Tonga clash as he reverts to his usual blindside berth, he admitted: “I certainly feel good. We’ve done a lot of training in heat and tough conditions. Everywhere we’ve gone, I said this last week, Portugal, Biarritz, being over here it’s been extremely hot and even back home was quite warm.

“A lot of that has stood to us fitness wise. It’s funny, we haven’t done a huge amount of out-and-out fitness work per se, kind of the old-school fitness term of just running and running. We’ve done loads and loads of rugby, and I think from a team perspective we’re quite rugby fit.

“I think last week will stand to people who played big chunks of that game or came off the bench, even who trained last week, the guys who put a big week in. It’s another big chunk in our fitness bank and (we’re) certainly feeling good.”

Tonga’s starting back row features the Scarlets’ Vaea Fifita, the former All Black, and Tanginoa Halaifonua and Sione Talitui fill the flanker roles. Big Bordeaux-based prop Ben Tameifuna leads the team as regular captain Sonatane Takulua starts on the bench.

O’Mahony’s recent Munster team-mate, Malakai Fekitoa, is a familiar face as is his centre partner Pita Ahki and full-back Salesi Piutau, who previously played for Connacht and Ulster respectively. Lock Leva Fifita left Connacht in the summer after two seasons.

With scrum half Augustine Pulu the fourth ex-All Black in Tonga’s starting XV, head coach Toutai Kefu commented: “(The former New Zealand players) have had a massive input already, both on and off the field.

“The biggest difference is off-the-field stuff – mindset, professionalism, a really good attitude, so that’s been refreshing and the younger players have observed that. They’ve raised the level of standard and expectation of all the players.

“We’re expecting to execute really well, execute our game-plan. Ireland are a very professional team, a very cohesive team. But we think there are some spots there we can identify and take advantage of.”

Having been a late addition to Ireland’s bench last week due to Robbie Henshaw’s injury, Connacht winger Mack Hansen will make his first World Cup start against Tonga. He has scored seven tries in 17 Tests, with six of them coming in the last year.

It has been a rapid rise for Hansen since his arrival in Galway just over two years ago, and his thorough professionalism on the pitch, mixed with his fun-loving personality off it, make him an ideal player to tour with, according to O’Mahony.

“Mack’s been a breath of fresh air. Obviously an incredible character. Good person, we talk about it a lot, the squad that we have and how important it is to fit in,” said the Munster captain, who was joined by Hansen at Thursday’s press conference.

Certainly you knew straight away he was a top man. As I said, a character but overall he’s an incredible athlete and one of the world’s best wingers at the moment, which is a great addition to have to the squad.

“The overriding factor is that he’s a good person and he’s seamlessly fitted into our squad like everyone else has. He’s great craic and you need characters like that. The beauty of the game of rugby is the different characters that you get, and we’d be lost without guys like Mack.

“Tours like this are made for being incredibly serious, obviously (it’s) our jobs and everything that goes with it. But the craic that fellas like this bring make it a great place to be.”

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