Millwall boss Gary Rowett said goalkeeper Matija Sarkic suffered a quadriceps injury a week before the final match against Birmingham City.
Sarkic, 26, joined Millwall on a permanent deal from Wolves this summer.
Since then, he has become the Lions’ No.
1, keeping two clean sheets in the opening five games of the Championship season, with Millwall claiming seven points.
But Sarkic recently missed an international match for Montenegro due to injury, and speaking to South London Press, Millwall boss Rowett revealed that Sarkic was injured before the match against Birmingham City earlier this month.
“Matty suffered a quadriceps injury a week before the Birmingham game.
He got through the match well but felt bad.
“We’re assessing this and trying to determine whether it’s a short-term injury or something a little more serious.
Hopefully it’s not too serious.
It’s disappointing given his form was brilliant – he saved the penalty against Birmingham.
“ another moment where you can see his qualities.
Millwall will return home to Leeds United this weekend, with the match taking place in front of Sky Sports on Sunday.
The options to replace Rowett are Bartosz Bialkowski and Connal Trueman, with Rowett hinting that Bialkowski will play on Sunday if Sarkic is absent.
Leeds United’s away trip will be very difficult for Millwall.
Daniel Farke’s side are off to a slow start but this month’s international break will be a good time to prepare and prepare for this match.
Sarkic’s potential absence is certainly a blow for Millwall, but in Bialkowski Rowett has a very experienced and reliable back-up option, and expect him to start from the start if Sarkic nor lose power.