There's a world in which Tadhg Beirne could have been playing against Ireland this Saturday, rather than for them.

However, as the Munster lock explains, it wasn't an idea he really entertained.

Having been let go by Leinster in 2016, the Kildare man shipped up in Llanelli with the Scarlets, and soon gave his former province, as well as Munster, something to chew on when he helped the Welsh side win a Pro12 title at the Aviva Stadium a year later.

When Munster and the IRFU came calling the following season, his then Scarlets head coach Wayne Pivac made a final play to keep the versatile forward.

"I didn't have a conversation with Warren [Gatland], but I did have a conversation with Wayne [Pivac] before I left Scarlets," Beirne says, speaking from Ireland's team base at Quinta do Lago in Portugal, ahead of this Saturday's Guinness Six Nations against Wales in Cardiff.

"He [Pivac] tried to encourage me to stay because he did say the World Cup was the following year and I'd be qualified for it,"

"But I think I’d made my decision before that, that I wanted to wear green for the World Cup, not to be in red.

"I only ever wanted to play for Ireland, that was the reality and I think when it became a talking point that there was an opportunity to play for Ireland, the only thing I wanted to do was come back and play for Ireland."

Beirne was instrumental in the Scarlets' Pro12 title win in 2016/17

Even if he didn't play for Wales, it's still a country that holds a special place in his heart, having given him the platform for a career which most recently saw him named to World Rugby Men's XV Team of the Year, as well as meeting his wife Harriet during his time at the Scarlets.

And those two years in Llanelli taught him a lot about the role rugby plays in everyday life in Wales.

"I learned that they're incredibly passionate about the Welsh flag, and the actual Welsh team. Watching those lads head off, they’d be very excited heading away and they were very passionate about playing for their country.

"It’s much like in here, and a lot of other countries, but I suppose when you’re from the outside looking in and you get to see that first hand how much it means to them, they show that at times, especially when they’re at home, how much playing for Wales means to them."

While Ireland and Wales come into the 2023 championship off the back of contrasting seasons, the majority of this weekend's squad have never won a Six Nations game at the Principality Stadium. Ireland beat Wales in Cardiff in pre-World Cup friendlies in 2015 and 2019, but it's 2013 since they last picked up a championship win away to the Welsh.

Beirne played in the two most recent defeats in Wales, the 2019 loss being his first appearance in the competition, and one he'd rather not remember, with Ireland hammered 25-7 in a championship decider.

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"That was my first experience of it (the Principality Stadium) and it really shocked me in terms of noise level, just the intensity of the game."

The most recent defeat was a 21-16 defeat on the opening weekend of the 2021 championship, where Ireland almost snatched a win, having played the bulk of the game with 14 men, following an early Peter O'Mahony red card.

"There were moments in that game that we just knocked off and we let them back into the game when we didn't need to… when we were exiting our 22 and forcing a few things and making silly errors there.

"I feel like we’ve learned and we’ve come a long way since that day. I think if you watch that game and you compare that to how we play now, we’ve come a long way.

"Someone made the joke in here, 'if you make a mistake how long does it last?’ and one of the lads said ’30, 40 years’ but in the moment you have to move on pretty quickly. But that will always probably sit in the back of my mind because that was one of those games that we could have won but we didn’t so you just have to move on."

After last year's series win in New Zealand, followed by November wins against South Africa and Australia, Andy Farrell's side come into 2023 as the top ranked team in the world, and are narrowly favoured over France to win their first Six Nations title since 2018.

And while Ireland haven't always dealt well with the weight of expectation, Beirne says they have to embrace the scrutiny that comes with the favourites' tag.

"We're ranked number one in the world, so no matter who we come up against, we have a target on our back.

"If we were playing the number one team, it would be the same thing, we’d want the scalp off them. It’s pretty exciting in my opinion and I look forward to the challenge when I get to be on the pitch to being able to put our best foot forward and hopefully maintain that number one spot.

"We’re here to win. That’s what we want to do.

"You’re talking about experimenting? I don’t know if I’ll be here this time next year in the Six Nations. Who knows? I want to be involved in every single game I can be and I obviously want to win this championship, I’ve never won it before. That’s the mindset of all of the players. And I think it’s pretty clear that’s the mindset of the coaches as well, that they want to win the Championship."

Follow every game of the Guinness Six Nations on RTÉ.ie/Sport and the RTÉ News app, or listen to live commentary on RTÉ Radio 1.

Watch live television coverage of Ireland v France (11 February), Italy v Ireland (25 February) and Scotland v Ireland (12 March) on RTÉ2 and RTÉ Player.