Gareth Southgate is sweating on the fitness of Trent Alexander-Arnold with fears a thigh injury picked up in Wednesday's 1-0 friendly win over Austria could rule the Liverpool defender out of Euro 2020.
The Liverpool right-back, 22, looked distressed as limped off late in the second half at the Riverside after injuring himself while clearing the ball.
"We're going to have a look. Clearly it's not a good sign to see him come off in the way he did," Southgate said.
"We'll have to assess him. I think it's a thigh but the medical team are assessing him.
"It's not a good sign to see him have to walk off as he did. We'll know more in 24 to 48 hours.
"We don't know the full extent. The last thing you want is to see him come off in the way he did."
Alexander-Arnold is one of four right-backs in the England squad along with Kieran Trippier, who was deployed at left-back against Austria, Reece James and Kyle Walker.
Unable to call on players from Chelsea, Manchester City and Manchester United following their European finals, Southgate sent out an experimental team.
Arsenal youngster Bukayo Sako staked his claim for a place in the starting line-up against Croatia at Wembley on June 13 with his first goal for England to cap an impressive display from left midfield.
"It's an amazing feeling for me, probably the biggest moment of my career," Saka said.
England complete their pre-tournament preparations with a friendly against Romania back in Middlesbrough on Sunday.
A section of the 8,000 crowd could be heard loudly booing England players when they took a knee in solidarity with the Black Lives Matter movement before kickoff.
"I did hear it. It's not something on behalf of our black players that I wanted to hear, because it feels like a criticism of them," Southgate said.
"Some people think it is a political gesture that they don't agree with, but that is not the case. I was pleased it was drowned out with applause."
