Kieran Tierney and Nathan Patterson are doubtful for Scotland's World Cup play-off semi-final against Ukraine in June, with both defenders requiring surgery.
Arsenal have confirmed "it is likely that Kieran will now miss the remainder of this season" with a knee injury picked up on international duty.
Everton manager Frank Lampard says right-back Patterson's season is also likely over due to an ankle injury.
"Nathan Patterson will be out for certain period of time," he said.
"He will have a small operation on his ankle later this week."
Both defenders face a battle to recover in time for Scotland's delayed semi-final with Ukraine, which is expected to be played in early June following the end of the domestic season.