Celtic duo Kieran Tierney and Leigh Griffiths have withdrawn from the Scotland squad for the opening 2018 World Cup qualifier in Malta on Sunday.
The in-form Hoops striker Griffiths flagged up a hamstring problem on Saturday after scoring his seventh goal of the season in a 4-1 Ladbrokes Premiership win over Aberdeen at Parkhead.
Midfielders James McArthur of Crystal Palace and Fulham's Kevin McDonald have also withdrawn for the game at the Ta'Qali Stadium.
Rangers captain Lee Wallace and striker Tony Watt, on loan at Hearts from Charlton Athletic, have been drafted in by boss Gordon Strachan.
Left-back Wallace won the last of his eight caps as a second-half substitute in a goalless friendly draw against the USA at Hampden Park in November, 2013.
The 29-year-old former Hearts defender was in the squad for the friendlies against Italy and France at the end of last season but withdrew.
Former Celtic forward Watt, 22, won his only cap to date as a second-half substitute in the 1-0 friendly win away to Czech Republic in March.
