Shaun Edwards admits Wales' opening World Cup warm-up game against Ireland has an element of journeying into the unknown.

After two months of training that included punishing camps in Switzerland and Qatar, Wales enter the competitive phase of their World Cup preparations at the Millennium Stadium on Saturday with four Test debutants and a new captain.

Scarlets centre Scott Williams leads a side containing newcomers Eli Walker, Tyler Morgan, Dominic Day and Ross Moriarty as the countdown continues to head coach Warren Gatland's 31-man World Cup squad announcement later this month.

“It is very unusual, particularly for some players playing for those World Cup spots, for your first game of the season to be the biggest game of your season,” Wales defence coach Edwards said.

“We are all competitive people, and any game of rugby that you go into you desperately want to win, particularly in front of your own fans.

"No-one kind of remembers who wins friendlies in six to eight months' time, but in the here and now it is very important for us because people are playing for spots and you want to get the momentum going into a Rugby World Cup.

“It is almost like we are going into the unknown a little bit because we have got a lot of players who haven’t played together before, and a lot of players we’ve seen play before but who are playing with players they haven’t played with before.”

Wales prided themselves on their fitness at the last World Cup four years ago, when a fourth-placed finish was their best on a global stage since 1987.

Edwards, though, knows it will be about the rugby this weekend as they build towards a tournament that sees them in the same pool as England and Australia, with just two quarter-final places available.

“We are pretty happy with where we are conditioning-wise,” he added. “We have put a lot of hard work in during those two camps.

“Let’s be honest, the best rugby team is going to win the World Cup, not the best athletics team. Obviously, being fit and well conditioned enables you to carry out the game-plan that you want to play, but in the end we are a rugby team, and the best rugby team is going to win the World Cup.

“It’s the first game of the season, and sometimes you have to tape back some of the enthusiasm, whether you are a 100-Test veteran or coming in for your first cap.

“You are not going to be massively in the groove as if you were six to eight games into a competition. It is important not to overplay, although it is the first game of the season.”