Hearts midfielder Cammy Devlin faces up to eight weeks out with a lower leg injury.
The Australia international, 27, sustained the injury during Tuesday’s 2-0 home win over St Mirren at Tynecastle, coming off in added time.
Devlin has made 27 appearances for the Scottish Premiership leaders this season, scoring once.
Capped four times for his country, the former Wellington Phoenix player is out of contract at the end of the season.
With Beni Baningime suspended for Hearts’ next league game, manager Derek McInnes will be without two of his key midfielders against Celtic on 25 January.
Hearts host Falkirk in Saturday’s Scottish Cup fourth-round tie.
