Aston Villa midfielder Barry Bannan has been called up to the Scotland squad for their World Cup qualifiers with Wales and Serbia.
The 23-year-old's inclusion comes after the withdrawal of James Morrison earlier on Tuesday.
It is understood the West Brom midfielder, whose two international goals have both come against the Welsh, sustained a hamstring injury playing against Stoke at the weekend.
The 26-year-old became the fourth player to pull out of boss Gordon Strachan's squad following the withdrawal of Ross McCormack, James Forrest and Danny Fox on Monday.
Norwich City defender Steven Whittaker has also been drafted in as former Celtic and Middlesbrough manager Strachan prepares for his first competitive game as national team boss with the visit of Wales to Hampden on Friday night.
McCormack, who was sent home because of illness ahead of last month's friendly win over Estonia, missed Leeds' game against Huddersfield on Saturday after suffering a head injury in their previous npower Championship match against Peterborough.
Fox, meanwhile, sat out Southampton's last two games after going off with a thigh injury in their defeat by QPR earlier this month and Celtic boss Neil Lennon confirmed at the weekend that Forrest would miss the international double-header with a back injury.