Marcus Rashford has withdrawn from the England squad for the games against the Czech Republic and Montenegro because of an ankle injury.
The forward sustained the issue during Manchester United's draw with Liverpool last month, and Gareth Southgate says he has now returned to Old Trafford, despite the efforts of England's medical team to get him fit.
Southgate said: "He's been with our medical team all week. We've tried to progress his training through the week, so he did some running with them.
"But it's clear to us he's not going to be ready for our matches, so we're going to send him back to the club. He's out of the two games."
Rashford's withdrawal comes as a blow to Southgate, who has used the striker in all of England's matches this season.
However, the manager believes Jadon Sancho and Callum Hudson-Odoi, the 18-year-old wingers who have three caps between them, are ready to step up and start for their country.
"We knew from a couple of days ago that Marcus wouldn't be ready for tomorrow," explained Southgate. "It's a great opportunity for the others because they've been exceptional in training. They look like they've been with us forever.
"We're really excited. We've lost a lot of players but there's opportunities for others. We're looking forward to seeing the team play."
When pressed on which of the duo was leading the race to start at Wembley, Southgate said: "It's difficult to say really because throughout the age groups they've been very similar.
"Jadon has obviously had more big-match experience and he has been with us for a bit longer. But Callum has fitted in brilliantly and we won't hesitate to start either of them in the game.
"They're ready. They can play, no problem for us."