Stuart Armstrong and John Souttar have withdrawn from the Scotland squad for the upcoming friendly matches against Peru and Mexico because of injury.
Midfielder Armstrong, 26, came off the bench as Celtic won Saturday's Scottish Cup final against Motherwell.
Uncapped Hearts defender Souttar, 21, missed his club's final two matches of the season.
Allan McGregor, Barry Douglas, Matt Ritchie and Ryan Fraser previously dropped out of Alex McLeish's squad.
The national coach has 21 players remaining in his pool for the games against Peru on 30 May and Mexico on 3 June (UK time), with goalkeeper Scott Bain, defender Stephen O'Donnell and midfielder Chris Cadden having been called up as replacements.
Revised Scotland squad
Goalkeepers: Jordan Archer (Millwall), Scott Bain (Celtic), Jon McLaughlin (Hearts).
Defenders: Jack Hendry (Celtic), Scott McKenna (Aberdeen), Charlie Mulgrew (Blackburn Rovers), Stephen O'Donnell (Kilmarnock), Callum Paterson (Cardiff City), Lewis Stevenson (Hibernian).
Midfielders: Chris Cadden (Motherwell), Dylan McGeouch (Hibernian), John McGinn (Hibernian), Kenny McLean (Aberdeen), Scott McTominay (Manchester United), Jamie Murphy (Rangers), Graeme Shinnie (Aberdeen), Ryan Christie (Celtic).
Forwards: Oli McBurnie (Swansea City), Lewis Morgan (Celtic), Matt Phillips (West Bromwich Albion), Johnny Russell (Sporting Kansas City).