Scotland's Scott McTominay has been sent home from the squad's training camp in Spain with a throat virus.
The 24-year-old Manchester United player will miss Friday's match in Moldova but could return for Monday's home tie with Denmark.
One more win for the Scots will secure a World Cup play-off place.
"It's disappointing to lose the player for this game, but it's a good chance for someone else to play in the team," said Scotland head coach Steve Clarke.
"We have good cover at centre back and in midfield."