McCormack joined up with the 28-man squad, but subsequently had to be sent home with flu symptoms.
The 26-year-old, who scored in a 3-1 friendly win over Australia in August, had been recalled to the squad by new Scotland manager, and ex-Leeds United midfielder, Gordon Strachan days after netting in the FA Cup victory over Tottenham Hotspur.
Leeds revealed McCormack had joined up with the squad, but had then been sent home with “flu symptoms”.
On his disappointing withdrawal, McCormack wrote on his Twitter account: “Gutted to be pulling out the Scotland squad ill...Now just rest and get fluids in me and be ready for Wolves on Saturday.”
Scotland manager Strachan has named Scott Brown as his first captain.
Celtic captain Brown will lead out the team for the first time ahead of tonight’s friendly.
“He already knows what it’s like to be a captain with pressure and that made him favourite,” Strachan said.
Gary Caldwell and Kenny Miller have shared captaincy duties in the absence of Darren Fletcher, who is battling a chronic bowel condition. But Caldwell has returned to Wigan with an injury and 33-year-old Miller is unlikely to start as the Vancouver Whitecaps striker is in the middle of his close season.
Strachan confirmed Caldwell’s withdrawal was one of several from his squad, adding: “He’s left. Grant (Hanley) has left too; they did well to come up, they’d really been struggling.
“Ross McCormack has left; he’s got some sort of bug, but he made it up here which was terrific.
“Young James (Forrest) went back because I felt it might be too much to play two games back to back for him. So he’s away to Celtic and they’ll look after him there.”
Strachan will make his debut as Scotland manager at the ground where he spent seven successful years as a player between 1977 and 1984.