England players Ben Chilwell and Mason Mount will have to self-isolate until Monday after coming into close contact with Scotland's Billy Gilmour, the Football Association has announced.
Both players will "isolate and train individually" in private areas at England's St George's Park training base until 28 June, the FA said in a statement.
It means the pair will miss tonight's Euro 2020 clash with the Czech Republic - and the decision has been taken in consultation with Public Health England.
The entire England squad and staff had lateral flow tests on Monday and all were again negative, as was the case with Sunday's UEFA pre-match PCR tests.
Further tests will be carried out as and when appropriate, the FA said.
Gilmour, who won the man of the match award for Scotland in the second group D match against England, tested positive for COVID on Monday after Friday's 0-0 draw.
In a statement, the Scottish FA said that Gilmour - who plays club football for Chelsea - will self-isolate for 10 days at the Rockcliffe Hotel, at Scotland's training base in Darlington.
He will not be available for the last-16 game if Scotland progress tonight against Croatia at Hampden Park in Glasgow.
Mount and Chilwell embraced and spoke to Gilmour on the pitch and are also reported to have spent 25 minutes with their Chelsea team-mate in the tunnel afterwards.
Pundit Gary Neville and broadcaster Gary Lineker have called the pair's isolation period "an absolute joke" and "ridiculous" on Twitter, calling for the players to just get tested.
Mount and Chilwell have both said separately on Twitter that they are "gutted" by the decision, but will be "cheering on" England in tonight's game.
The pair could potentially miss England's first Euro 2020 knockout game depending on the outcome of tonight's final Group D matches.
If England top the group, they will play the second-placed team in Group F (Portugal, France, Germany, Hungary) at Wembley next Tuesday.
But if Gareth Southgate's side are runners-up in Group D, they will play the runners-up of Group E (Spain, Sweden, Poland, Slovakia) next Monday - meaning Mount and Chilwell will be unavailable.
If England finish as one of four best third-placed teams, a situation which would require them to lose to Czech Republic and for Scotland to beat Croatia by a significant margin, they will play either the winners of Group C or Group B on Sunday, or the winners of Group E on Tuesday.