Rangers' Ryan Jack is set to miss Scotland's Euro 2020 play-off with Israel and possibly the first Old Firm game of the season with a calf injury.
The midfielder limped off in the early stages of Saturday's 4-0 Scottish Premiership win over Dundee United.
And manager Steven Gerrard has confirmed Jack, 28, will miss "a few weeks at least" with the problem.
Scotland welcome Israel on 8 October, with the Old Firm game at Celtic Park nine days later.
"We need to take it day by day," Gerrard said.
"He will certainly be missing in the short term but it's difficult to say if it will be two, three or four weeks at the moment.
" Jack started the Nations League match against the Israelis earlier this month, but was an unused substitute against Czech Republic three days later.
Gerrard already faces being without Joe Aribo for the Old Firm game after the midfielder was ruled out for up to six weeks with an ankle problem.
However, winger Brandon Barker's hamstring problem is not expected to keep him out for a prolonged period and Alfredo Morelos is fit for Thursday's Europa League game with Lincoln Red Imps.