In normal circumstances, England wouldn't consider taking a risk with Jason Roy or Jofra Archer. These are the men they hope will open the batting and bowling in not just the knockout stages of this tournament, but in the Ashes that follows on its heels. They are precious assets.

But these are not normal circumstances. And such is England's need to win on Sunday at Edgbaston - they could still progress if they lose, but it would require good fortune with other results - that Eoin Morgan, the captain, has confirmed that both will play if they come through fitness tests on the morning of the match even if it risks exacerbating their injuries.

Roy has missed England's last three World Cup games - two of which have been defeats - after sustaining a hamstring injury during the match against West Indies. His replacement, James Vince, has managed just 40 runs in three innings while Roy has passed 50 in five of his last six ODIs in a spell that includes two centuries. In his absence, his value has become abundantly clear.

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Archer, meanwhile, has been suffering from some stiffness in his side. His average pace has dropped a little in that period and he did not bowl in training on Friday. But even with that discomfort, he bowled at 92mph at Lord's. He has quickly become one of England's most valuable bowlers: threatening at every stage of the innings. Both men are, in short, some way better than their potential replacements.

"Jason is preparing to play tomorrow," Morgan said on Saturday. "Provided he gets through today's practice and tomorrow morning unscathed. We think he might be fit to play.

"If him playing is going to rule him out long-term, then absolutely not," Morgan said in reply to a question asking if Roy would be risked for the game. "But if it's going to rule him out for a couple of weeks, yes.

"The exact same thing applies [with Archer]. If it's long-term (risk), then no. if it's short-term, then yes. Again, we're going to see how he comes through today. It's the same thing he's been playing with the last three games."

There were moments on Saturday when it didn't seem Archer was especially likely to get through any fitness session. After bowling one delivery off something approaching a full run - albeit wearing a cap - he left the pitch with the team doctor only to reappear a little while later and bowl several overs of spin. The team management seem confident he will be fine.

England might also bring Liam Plunkett back into their team. They are anticipating a very good batting track - Ashley Giles, the England team's managing director, reckons it may be the best batting surface this tournament has seen so far - which will offer very little to spinners or seamers. As a consequence, they are considering dropping Moeen Ali, who has not enjoyed the best of campaigns, to make space for Plunkett's back-of-a-length cutters. Edgbaston's wide square boundaries may well suit them. And, if England require some spin support for Adil Rashid, they can utilise Joe Root.

Jason Roy of England speaks with captain Eoin Morgan during a nets session at Headingley Getty Images

The reading of the pitch could yet prove crucial. The India team management, having watched previous games on the ground (not just in this tournament, but in the Champions Trophy of 2013), seem confident the pitch will spin and look set to include two specialist spinners and one part-timer. If either England or India have misread the conditions, they could be exposed.

While the conspiracy theorists will suggest England are getting the pitch they demand, the truth is a little more mundane. It has simply stopped raining in England in recent days and the groundstaff have, at last, had a decent amount of preparation time. Had the weather been better, it is likely nearly all the surfaces in the tournament would have been this good. Besides, a surface enjoyed by England's batsmen, may well be a surface enjoyed by India's too.

"We want to play on best possible batting wicket and we always do," Morgan said. "We bat deep and we bat strong. It's an area we're more confident. Everybody knows that. On those wickets, we don't have to think about adapting too much or fighting our natural game. We can just go out and play.

"But where we've let ourselves down as a group is adapting to conditions. We haven't adapted well enough. It's been a bigger challenge in this World Cup than previous bilateral series that we've played. It's been the most difficult part of the World Cup. Tomorrow is going to be the same. We're going to have to adapt to conditions and to playing against a strong side in India.

"We going to be clear about how we're going to go about it. We're going to show a huge amount of positivity in the way we play and back it with the courage to play that way."

One area India might have an advantage is in the level of support. While the percentage of ticket-buyers expressing an allegiance to India at the point of sale was around 55, it is understood some tickets may have changed hands subsequently. It will, Morgan admitted, leave England feeling they are playing away from home.

"I sort of recall the Champions Trophy final we played here against India in 2013," he said. "It was a complete away game. We had a number of fans in the ground, but the noise the Indian fans make with horns makes it that much louder. So yes, tomorrow will feel like an away game."

While Jonny Bairstow's comments may have given a picture of a tense England camp, the reality appears quite different. Training over the last couple of days has been as relaxed as ever with no sign of the importance of the game ahead. We have seen tense and divided England sides before: this does not look like one of those at all. Even a somewhat bruised Bairstow, who feels the humour in his words was lost in the publication process.

"We haven't performed well, so critics are going to be critical," Morgan said. "They're entitled to their own opinion. I think the support that we've had from our fans and everybody around the country has been unbelievable. It has been outstanding. There's been an enormous amount of goodwill going around, and it's making our tournament that much more special to be a part of and to play in."

And there's the rub. To remain part of it, they have to beat the world's No. 1-ranked ODI side on Sunday. It is a scenario that could - should, really - have been avoided. But it's only a year since they defeated them in an ODI series in England and only a week since they were the No. 1 side themselves. These are the big games in which these players love to be involved. They have enjoyed some fine moments over the last four years and they have been building to just such a moment throughout. Now it really is time to put all that work, all that talk and all that progress into action. It's time to deliver.