The Wolves striker will have a foot injury assessed today by the Hampden medical team but is a major doubt for Tuesday's game.
Defender Steven Whittaker is carrying a calf knock and will also be assessed but striker Chris Iwelumo is again out with a hamstring injury which caused him to miss the draw against Lithuania in Kaunas on Friday night.
Defenders Lee Wallace and Kevin McNaughton are back in the squad after missing the Lithuania match with foot and groin injuries respectively.
Goalkeeper Iain Turner has been drafted in as a precaution after David Marshall hurt his elbow.
Scotland assistant boss Peter Houston said on Sunday: "Whittaker might not train today but should be okay.
"Fletcher will be assessed later this morning and the physios and doctors will let us know.
"Iwelumo is out, he didn't turn up, he was struggling.
"But Lee Wallace has turned up and he will do some work with the physios and Kevin McNaughton will join us."
Houston played down the loss of two points in Kaunas which leaves Scotland probably having to pick up points away from home against Spain and the Czech Republic.
He said: "We came away from a difficult fixture with a clean sheet.
"It would have been nice for us to score and we are disappointed that we didn't but we look forward rather than look back."