Scotland have been dealt a huge blow ahead of Tuesday night's game with Croatia after returning a positive Covid-19 test.
The former Rangers youngster was named man of the match in his first start against England on Friday night but will now miss the clash at Hampden.
It's a cruel blow to both the player and Steve Clarke who hoped he would be a key player again when they take on Croatia for a place in the last 16.
Scotland must beat Croatia at Hampden to have a chance of qualifying as one of the best third place teams but will have to do without the Chelsea midfielder.
So far, no other players have been ruled as close contacts but Gilmour will now have to isolate for 10 days, meaning he would also miss any last 16 tie if Scotland did qualify.
A statement from the SFA said: "The Scottish FA can confirm that a member of the Scotland National Team playing squad, Billy Gilmour, has tested positive for COVID-19.
"Having liaised with Public Health England since the positive test was recorded, Billy will now self-isolate for 10 days and therefore miss tomorrow’s UEFA EURO 2020 Group D match against Croatia at Hampden."
Gilmour is the second Scotland player to test positive after fellow former Ibrox midfielder John Fleck was forced to isolate during their warm-up camp in Portugal earlier in the month.
