Scotland interim coach Billy Stark has called up a trio of uncapped players for the international against Luxembourg on Wednesday.
Inverness midfielder Andrew Shinnie, Hibernian striker Leigh Griffiths and Kilmarnock midfielder Liam Kelly have all been drafted in following a string of withdrawals.
Nine players from the initial squad have pulled out due to injury and Stark will use the opportunity to introduce fresh faces to his party.
James Morrison, Phil Bardsley, Steven Fletcher, Shaun Maloney, Charlie Adam, Matt Phillips, Barry Bannan, David Marshall and Jamie Mackie are the missing players.
St Mirren goalkeeper Craig Samson and Huddersfield left-back Paul Dixon, who have featured in recent squads, have also been called up.
"Obviously at this stage of the season, with weekend and midweek games, niggles, strains and withdrawals are to be expected," U21 coach Stark told the SFA website.
"This match gives us a chance to look at players who maybe have not had experience of the international set-up but who have been in tremendous form for their clubs.
"Leigh has been excellent for Hibernian and scored again yesterday. I know him from the U21s and he is a talented player.
"Liam has been terrific for Kilmarnock and it is fitting that he gets an opportunity, while Andrew has been a real inspiration behind Inverness's success so far this season."