Alun Wyn Jones, the world's most capped lock

Cardiff (United Kingdom) (AFP) - Wales host Ireland in the Six Nations on Saturday in the knowledge that victory will seal a Grand Slam.

AFP Sport looks at three key match-ups for the crunch game.

Jones and Best - talismanic skippers

Wales’ Alun Wyn Jones, the world’s most capped lock, will win his 134th cap when he takes to the field in Cardiff, while Ireland hooker Rory Best will feature in his 64th and final Six Nations game.

The two veterans have been lynchpins for their respective teams, Jones an all-rounder whose ball-carrying and tackling belie his 33 years and 36-year-old Best, capped 116 times by Ireland, a key component of his side’s attacking line-out who is also immensely strong over the ball.

While Jones appeared in nine Tests for the British and Irish Lions, Best has had to be happy with a starring midweek role, but that has not deflected either from his qualities as player or leader.

“He’s been a brilliant captain for us over the years,” Ireland playmaker Jonny Sexton said of Best. “Always team first, Always very selfless and leads on the pitch with his actions. He leads off the pitch too and he’s a great character to have around.”

Wales coach Warren Gatland said Jones had “matured gracefully”, hinting the lock might delay his retirement from international rugby given the form he’s in.

“In the early years he was a bit hot-headed and temperamental and he was the one starting the fights in training,” Gatland said.

“That is what a competitor he is. He has been very important to us, he is a player who does not pick up many injuries and has been a constant. He is pretty valuable.”

Parkes v Aki, a Kiwi-accented midfield

Hadleigh Parkes touched down in Wales from New Zealand in 2014, making his debut for his adopted country after three years of residency. The tough-running, defensively strong centre made his Super Rugby debut for the Auckland Blues alongside current Wales fly-half Gareth Anscombe back in 2012, the same year Wales last won the Six Nations Grand Slam.

Parkes’ Ireland counterpart Bundee Aki, a 2013 Super Rugby champion with the Chiefs, followed a similar path. Auckland-born of Samoan descent, Aki arrived at Irish province Connacht in the same year Parkes signed for Scarlets.

“We go way back to battles we’ve had at New Zealand provincial level, Super Rugby level and in the Pro14 with the Scarlets against Connacht,” Parkes said of Aki.

“I’m super pleased for him with the way it’s gone since he came over to Ireland. He’s a go-to man for them with go-forward ball. He carries well, but defends well too. It’s going to be a tough challenge, but it’s exciting because we know each other so well. Hopefully afterwards I’ll have the bragging rights against him!”

Sexton headlines halfback clash

Gatland is in no doubt about what threats the Irish halfback pairing of Connor Murray and Sexton throw up. Wales’ coach picked the duo as his starting number nine and 10 for the drawn British and Irish Lions series against New Zealand in 2017.

“Johnny is world player of the year and absolutely world class,” Gatland said.

“We’ve got to try and not give him as much time on the ball and not allow him to dictate the game to us. We’ve got to put him under pressure.”

While Murray has not quite hit the form he enjoyed a couple of years ago, Wales have dabbled with their recent scrum-half selections, handing three starts to Gareth Davies, Aled Davies and Tomos Williams. Gareth Davies will start on Saturday, pairing up with Anscombe.

The pressure will be on Anscombe, the fly-half born in New Zealand to a Welsh mother, and Davies to produce a kicking game that helps contain what will surely be a rampant Irish forward pack expertly directed around the Principality Stadium by Murray and Sexton.