John McGinn has been ruled out of Scotland’s Nations League double header against Croatia and Portugal due to injury while Steve Clarke has called up Nicky Devlin, Liam Lindsay and Andy Irving for the first time.
There is also a return for 41-year-old goalkeeper Craig Gordon as well as striker Che Adams, who missed the defeats against Poland and Portugal last month due to injury.
Gordon was not selected for the Euros but the Hearts goalkeeper has been offered a surprise recall alongside Angus Gunn and the uncapped Dundee goalkeeper Jon McCracken.
Preston centre-back Lindsay and Aberdeen right back Devlin have been brought in to offer much-needed cover to defensive positions, with Scott McKenna also ruled out and Kieran Tierney, Nathan Patterson and Aaron Hickey all still unavailable due to injury.
West Ham midfielder Devlin replaces the injured McGinn, who has been ruled out of his Aston Villa’s Champions League fixture against Bayern Munich this midweek due to a hamstring problem picked up in the recent win over Wolves.
Scotland lost both of their opening Nations League games last month to late goals, with a 97th minute penalty earning Poland a 3-2 win at Hampden and Cristiano Ronaldo scoring an 88th winner for Portugal.
Scotland will travel to Croatia on Saturday 12 October before hosting Portugal at Hampden on Tuesday 15 October, as Clarke’s side look to end their winless streak that dates back to before the European Championships.
Scotland are without a win in their last eight competitive games, the worst run in their history, and have won just one of the last 14 games, against Gibraltar.
And Clarke must also now overcome an injury crisis that has left his squad looking thin ahead of games against high-class opposition, with Portugal 8th in the world and Croatia 12th.
Former Hearts midfielder Irving has made three substitute appearances for West Ham this season, while former Partick Thistle defender Lindsay is a regular starter for Preston in the Championship.
Devlin, 30, also receives his first international call-up after helping Aberdeen to their impressive start to the Premiership season, where they sit joint-top of the table after six games.
It was thought Gordon had made his last appearance for Scotland when he became the country’s oldest-ever international against Finland in June, which came after he missed out on the Euros squad.
But the 41-year-old could add to his 75 caps after reclaiming his starting place at Hearts.
Meanwhile, Scotland have confirmed that assistant coach Austin MacPhee has left Clarke’s coaching set-up.
The set-piece specialist stepped down because of his father’s illness and in order to focus on his club role with Aston Villa, which is more demanding this season with the club returning to the Champions League.
Scotland squad to face Croatia and Portugal
Goalkeepers: Craig Gordon (Hearts), Angus Gunn (Norwich City), Jon McCracken (Dundee)
Defenders: Nicky Devlin (Aberdeen), Grant Hanley (Norwich City), Liam Lindsay (Preston North End), Ryan Porteous (Watford), Anthony Ralston (Celtic), Andrew Robertson (Liverpool), John Souttar (Rangers), Greg Taylor (Celtic)
Midfielders: Ryan Christie (AFC Bournemouth), Ben Doak (Middlesbrough – on loan from Liverpool), James Forrest (Celtic), Ryan Gauld (Vancouver Whitecaps), Billy Gilmour (Napoli), Andy Irving (West Ham), Kenny McLean (Norwich City), Scott McTominay (Napoli), Lewis Morgan (New York Red Bulls)
Forwards: Ché Adams (Torino), Lyndon Dykes (Birmingham City), Lawrence Shankland (Hearts)