Wales skills coach Neil Jenkins revealed on Monday that the winger had yet to integrate fully with the rest of the squad's training, having suffered three concussions, and that he had not attempted the return-to-play protocols ahead of the match at the Millennium Stadium.

North, a pivotal player for the national team, has not played for club or country since March. However, Jenkins was hopeful that he would be available for the second warm-up game against the Irish in Dublin in three weeks' time, which is less than a month before Wales's opening match of the tournament.

"George has been doing most of the stuff with the rest of the guys," Jenkins said. "He is still picking up on a few things and that's to do with the medical staff. But he is going pretty well and has done a lot of skills and a fair bit of rugby stuff as well. I am sure he could be involved in the Dublin game." Wales are expected to name a mostly second-string side on Tuesday.

Jenkins said the squad's training camps in Switzerland and Qatar had been so fearsome that he feared some of the squad would withdraw. "The boys have been working incredibly hard," he said. "It was tough and brutal. To see the workload they get through was pretty incredible and I am in awe of them. If you see it first hand you do question whether it's really necessary, but it is to win a World Cup. It gets to a point where they are training that hard you wonder if someone is going to drop out."

Wales prided themselves on their fitness during the last World Cup in New Zealand, but it appears that standards have risen again. "The training has been harder than 2011," said flanker Justin Tipuric. "It's tough – the toughest training I have experienced, without a doubt. But it's what you expect. You are going to a World Cup and you don't expect it to be easy."

And it will not be easy in a qualifying pool with England and Australia. "All the other sides are doing what we are doing," Jenkins added. "We need to be in the best possible shape to give ourselves a chance to get out of that group. We know what we are up against."

Wales are mindful that they lost 62-5 to England in a warm-up Test in 2007. "I would like to think we are not going to go down that road because that was a very bad day," Jenkins said. They could still, then, field some seasoned internationals such as Alex Cuthbert, Mike Phillips, Richard Hibbard, James Hook and Tipuric on Saturday.

In a match that is already sold out, there will also be keen eyes trained on uncapped players such as Gareth Anscombe, Ross Moriarty and Tomas Francis as head coach Warren Gatland looks to whittle his squad down from 46 to about 36 after the game.

"I would have thought some players will be a little bit twitchy and they would not be human unless they were getting a bit nervous," Jenkins said. "Whatever the team is going to be on Saturday, it's a fantastic chance for the guys playing to put their hands up and give Gats a headache. We want to give them the best chance to stake a claim."

The fitness of tighthead prop Samson Lee, who injured an Achilles tendon against Ireland during the Six Nations, is causing concern. But he is so vital to Wales – even more so than centre Jonathan Davies, whose absence from the tournament will be keenly felt – that they will consider selecting him in the 31-man squad even if he is not fully fit by the August 31 deadline. They will do the same with wing/full-back Liam Williams, who has had foot surgery.

"They are both extremely talented rugby players and important to our team," Jenkins said. "If we can get these guys fit they will make a big difference to our squad. It is up to Gats when the time is right to see if these guys are right. Both are going extremely well and we would like to think they can play their part in this World Cup."

The Telegraph, London