Wales will have to deal with a mounting injury crisis when they take on hosts England at Twickenham on Saturday in a crucial 2015 Rugby World Cup Pool A encounter. With only two from three of England, Wales and Australia making it through to the quarterfinals, it is a match that promises to have huge consequences.

England and Wales both got off to expected winning starts in the competition over the weekend, with the former eventually coming good to beat Fiji 35-11 and the latter brushing Uruguay aside, 54-9. But the Welsh win came at a significant cost.

Samson Lee, Liam Williams, Paul James and Aaron Jarvis all suffered injuries that remain under assessment, but the major casualty was center Cory Allen, who will not play any further part in the competition due to a hamstring strain. With Leigh Halfpenny and Rhys Webb having already been ruled out ahead of the World Cup, it leaves coach Warren Gatland’s plans in disarray heading into the showdown with England. The mounting problems have also brought extra scrutiny to their intense preparation for the event. Gatland, though, has rejected the suggestion that his players were overworked.

“I don’t think so,” he said. “We know we are in good shape. Sometimes you just get a little bit of bad luck and we feel that’s what we’ve had at the moment. Cory Allen has pulled a hamstring and the other look like they could be a week or three or four days knocks. It’s just what happens at this level. I don’t think you can blame the preparation on Leigh Halfpenny and Rhys Webb getting injured, they were just unlucky.”

Excluding the injuries, Wales would have reason for confidence going into Saturday’s game. Gatland’s side has won three of its last five meetings against England, including a victory at Twickenham three years ago. Still, England have had the upper hand of late, and triumphed at Cardiff’s Millennium stadium at this year’s Six Nations.

England’s long quest to lift the World Cup on home soil finally began in earnest last Friday, but it was a stuttering performance against Fiji. Indeed, it wasn’t until the final 20 minutes that England pulled away to earn a bonus point for scoring four or more tries, thanks in no small part to coach Stuart Lancaster’s substitutions. Former Rugby League player Sam Burgess and No 8 Billy Vunipola were among those to catch the eye, and Lancaster has not ruled out making changes to his lineup against Wales.

“We’ve never said we were going to pick the same team week in, week out,” he said. “We select it on a week-by-week basis, assess the performance and decide what’s best to play Wales. We know them pretty well, we know the quality of the players they’ve got in their team, and how well Warren Gatland and Shaun Edwards and these guys will have them prepared to play us.”

Where: Twickenham Stadium, London

Date: Saturday, Sept. 26

Time: 3 p.m. EDT