Midfielders Darren Barr and Murray Davidson have been called up to the Scotland squad to face Luxembourg.
St Johnstone midfielder Davidson's call-up was confirmed by the Scottish Football Association while Hearts revealed Barr had been picked.
Caretaker manager Billy Stark has now added seven players to his original squad after nine withdrew on Sunday.
Barr has one Scotland cap, earned while a Falkirk defender in a goalless draw against Northern Ireland at Hampden in August 2008.
His career stalled after a move to Hearts but he finally won a regular first-team place earlier this year after being converted to a defensive midfielder. The 27-year-old scored in the William Hill Scottish Cup final win over Hibernian and has been an ever-present this season.
Davidson, 24, is uncapped but was previously called up for matches against the Faroe Islands in November 2010 and Brazil in March 2011.
He told St Johnstone's official website: "I'm delighted. I've been involved before and got on the bench in games against the Faroes and Brazil but have been out of the scene for a wee while so it's great to be given this chance."
The call-ups mean Stark now has 19 players booked to travel to Luxembourg.
Stark handed debut calls to Kilmarnock midfielder Liam Kelly, Hibernian striker Leigh Griffiths and Inverness midfielder Andrew Shinnie on Sunday. Huddersfield left-back Paul Dixon, who played in the opening World Cup qualifiers against Serbia and Macedonia, and St Mirren goalkeeper Craig Samson were also brought in.
Cardiff goalkeeper David Marshall (groin), Sunderland pair Phil Bardsley (hamstring) and Steven Fletcher (ankle), midfielders Shaun Maloney (abdominal), Barry Bannan (knee), Charlie Adam and James Morrison (both groin), Blackpool winger Matt Philips (toe) and QPR forward Jamie Mackie (ankle) all pulled out.