Assistant coach Steven Reid said: “It’s disappointing. Grant has missed a little bit of football and unfortunately is not going to be with us, and Ryan as well.

“He performed really well in the past camp so that is a blow but we have got strength in depth.

“We have obviously bigger numbers than usual in the squad and feel as if we have a squad which is capable of competing well at our strongest in the Serbia game and going into the two Nations League games after.”

Scotland’s preparations last month were hit by a positive Covid-19 test for Stuart Armstrong, which also took Ryan Christie and Kieran Tierney out of the squad.

Manager Steve Clarke also suffered further call-offs through injury and suspension during the triple header but his team still managed to record a hat-trick of wins, against Israel in the play-off semi-final and over Slovakia and Czech Republic in the Nations League.

“What has been pleasing in the last couple of camps is, despite the injuries and the issues with the Covid situation, the lads that stepped up were first class and that’s going to be the same going into all of these games as well,” said Reid, whose side round off their Nations League campaign in Slovakia and Israel this month.

“If there was to be an issue, we have players who have stepped in and stepped up to the plate.

“Going into this game, there’s players who have played a lot more games, who are getting up to a bit more match speed.

“We went into the last couple of camps and still had the issue with pre-seasons and getting up to match tempo. But by now the lads have played a lot of games.

“The squad is still strong. I have not been in a squad yet with Grant so he has not been part of it for a little while anyway. It’s still a shame he is missing out but it’s still a squad more than capable of getting a result.

“And the motivation and the prize at the end of it is hopefully going to take us up to another level of performance.”