Joe Cokanasiga and Mark Wilson have emerged as potential doubts for England’s opening match of the World Cup against Tonga next Sunday with both players carrying knee problems.

They have been unable to take part in full training at England’s training base in Miyazaki, instead undertaking what Eddie Jones has described as a “mini pre-season” before the Group C game in Sapporo.

Jones expressed a degree of optimism on Saturday that both would be fit to face Tonga in Sapporo but on Sunday the England defence coach, John Mitchell, could not confirm whether they would be available for selection following England’s first full-on training session.

Both players were involved in England’s final warm-up match against Italy in Newcastle – Wilson starting at flanker and Cokanasiga coming off the bench.

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“When guys get knocks and niggles they go through a rehab process based on a specific injury,” Mitchell said. “Like anything, you want to return back into the way that we train, so it’s important that you increase their high speed and ability to accelerate and cope with the way we do train. That’s generally the model or process for everyone, not just Mark and Joe.”

Jamie George has revealed he has been preparing for the humidity in Japan by dipping balls in buckets of water before throwing into the lineout during training.

“We’ve been doing it for a while now but we have buckets on the side of the pitch and we put the ball in that before we throw it,” the England hooker said. “We’re the lucky ones because we get a towel before we throw, so we’re at least allowed to dab it down a bit. We saw it in training yesterday – the ball is slippery.

“We might not have the benefit of a towel each time, so we make sure we don’t use towels too much in training. It’s obviously beneficial if we get a towel in a game. It doesn’t make too much of a difference to us as lineout throwers. You just have to make sure you grip it and hope for the best.”

Ritchie to miss Scotland’s opener with Ireland

Flanker Jamie Ritchie is set to miss Scotland’s World Cup opener with Ireland, but Gregor Townsend says he is glad not to be dealing with a more serious casualty list.

Edinburgh forward Ritchie suffered a broken cheekbone against Georgia at Murrayfield last week. He underwent surgery to have a titanium plate fitted before flying out to Japan, and is expected to be fit for Scotland’s second game, against Samoa.

“[Jamie] is still recovering from the operation and also jet lag, so he’s not training with us just yet,” Townsend said. “He’s unlikely to be available for the Ireland game but he will be back in full training after that.”

“We had four players who went to hospital [after the Georgia game] and two who had to be removed because of head injuries. But all of them are available to play in the World Cup,” Townsend added. “That means we’re in the best possible condition to play well.”

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Wales are set to be without locks Adam Beard and Cory Hill for their World Cup opener against Georgia on 23 September. Ospreys forward Beard will fly out to Japan on Thursday after staying behind in Wales to haved his appendix removed.

Hill is continuing his recovery from a stress fracture in his leg, and is on target to be available against Australia six days later, while fly-half Rhys Patchell has resumed non-contact training after suffering a concussion in the warm-up against Ireland.

“We will ease [Rhys] back into contact work later in the week, making sure that we go through the protocols and ensure he’s 100% and available for selection,” said the Wales head coach, Warren Gatland.