Marc Guehi and Anthony Gordon are expected to miss England’s final two World Cup qualifying games through injury.
Defender Guehi suffered a foot injury in Crystal Palace’s midweek Conference League win that left him unable to walk.
Newcastle winger Gordon missed Sunday’s defeat by Brentford with a hip issue, with manager Eddie Howe later confirming to BBC Sport he will be ruled out of international duty.
Magpies and England keeper Nick Pope also picked up a suspected concussion in the 3-1 loss.
England, who have already qualified for next year’s World Cup, will face Serbia at Wembley on Thursday before playing Albania in Tirana next Sunday.
Palace boss Oliver Glasner confirmed the extent of Guehi’s injury on Sunday before their match at home to Brighton, saying the player would miss the Premier League game with “a heavy bone bruise”.
The incident happened at the end of the 3-1 win over AZ Alkmaar on Thursday as the Palace captain conceded a yellow card for a foul.
“Overnight he couldn’t sleep, it was so painful and the next day we assessed him and it was a heavy bone bruise,” Glasner told Sky Sports.
“He was walking on crutches the last two days and couldn’t even step on his foot.
“Fortunately nothing is broken, but at the moment he can’t even walk. It looks like he will miss England’s games, but after, maybe in 10-14 days hopefully he can return to training and be available again.”
England’s players are due to report for duty on Monday.