Whisper it quietly in the valleys but this Wales team are breaking new ground even before they go into Sunday's game against Fiji with a place in the quarter-finals all but guaranteed. As near as makes no difference the squad have been dry since the summer and if there is any celebrating to be done on Sunday night it will involve no more than two bottles of beer.

"There is no binge drinking," says the increasingly impressive Wales captain, Sam Warburton, who is reckoned to be as much a leader off the field as he is in scooping up man-of-the-match awards on it. "After the game the players will be allowed to have a bottle or two if they feel they need to, if it helps them to relax but there will be no binge drinking. A while ago, players might have gone out after every game but now you have to see the bigger picture. There is no point working so hard since summer, just to have a drink in the group stages."

Warburton says there has been a massive change in attitudes in the Wales camp since Andy Powell – on the bench against Fiji – was dropped 19 months ago for driving a golf buggy on the M4 while over the limit. And the change is being driven by the younger internationals.

"There are quite a lot of young guys coming through now who are very keen when it comes to training, when it comes to recovery, when it comes to not drinking, eating the right food, and it's rubbing off on the rest," the Cardiff flanker said. "That's why we had two dry camps in Poland. They are changing the way of the Welsh culture a few years ago."

However, even before those training camps at Spala, where players submitted themselves to temperatures of minus 120C so they might train longer and harder, a new regime had kicked in. "We had what we called a dry board in the summer," says Warburton. "Everyone started off dry and if you had a drink – even a glass of red wine with your wife – you moved to the wet set. It was an honesty call and there were about 10 players left on the dry side, which was pretty good. Every one is showing a high level of commitment."

Some change from the past, when Welsh players roaming Cardiff were common currency after home internationals. "Drink has been a large part of our culture, especially at club level," Warburton says. "My brother plays in Division One of the Premiership and I know drinking is a big part down there but there is no room for that here and now.

"There were instances in the Six Nations even a couple of seasons ago with Andy Powell, but after this Six Nations on the bus back, maybe the coach, maybe the manager would say: 'Nobody is going into Cardiff tonight. If you want to go into the bar you are more than welcome but you are in bed by 12 o'clock,' and that has been the way forward."

The result is there for all to see. Wales are one of the fitter sides out here and go into the quarter-finals believing they can equal or better the side of 1987 who were the last Welsh team to get on the podium, taking third place in the first World Cup, held here in New Zealand.

According to Warren Gatland, the coach who has presided over the rise in form and makes seven changes for Sunday, the squad have not focused on the last World Cup, when his predecessor Gareth Jenkins lost his job after defeat by Fiji, or the draw in Cardiff last November.

He believes this team are much stronger than the one who finished 16-16 at the Millennium Stadium and said he might then have taken Fiji too lightly as he looked ahead to the World Cup. "Absolutely and I think it's the youngsters who have been performing incredibly well for us. It's also nice that after injuries some of the more experienced players have been coming back and fighting for position.

"When you are building up for a World Cup, you have to look at certain games where you try to develop some depth and give youngsters an opportunity. Sometimes in the past, against Fiji and even in the Six Nations against Italy, I've been guilty of that and nearly come unstuck. But you have to believe in the pathway and what you want to achieve and hopefully turn up at this tournament in good shape and with some depth as we have that at the moment."

On Sunday he underlines the new depth of the squad by resting Jonathan Davies and keeping the partnership of Scott Williams, a hat-trick scorer against Namibia, alongside Jamie Roberts in midfield, while Rhys Priestland starts ahead of Stephen Jones, despite being understudy at the Scarlets to the man who has just set a record of 101 caps. Gethin Jenkins, the flanker Ryan Jones and the full-back Lee Byrne have also been retained.

As for Warburton, he as usual will be in the dry camp on Sunday night. Win or lose it will be the same. "You can count on one hand the number of times I drink in a year. Maybe at the end of season. I don't like going out after games. My body is hurting and my shoulders are hurting. Going out is the last thing I want to do, so I come back to the hotel and have a quiet one. I may go to the corner shop and buy myself a bar of chocolate and take it easy."

The Tafia will be turning in its collective grave.