The Scottish FA has confirmed Scotland will play European champions Portugal in a friendly at Hampden on 14 October.
Scotland had one free fixture date following a trip to face Israel on 11 October in their inaugural Nations League campaign.
Alex McLeish’s side will also play Peru (29 May), Mexico (2 June) and Belgium (7 September) in challenge matches later this year.
They open their Nations League campaign at home to Albania on 10 September.
McLeish, who made his Scotland debut in a 4-1 win over Portugal in 1980, watched his team beat Hungary after losing to Costa Rica in their recent friendly double-header.
Portugal last played Scotland in a 2002 friendly in which Pauleta scored twice in a 2-0 win against the Scots.
“Portugal will provide a stern test for our players, which is exactly what we are looking for in our opposition in challenge matches,” McLeish told the SFA’s website.
“The recent challenge matches against Costa Rica and Hungary were invaluable to myself and my coaching team, allowing us to get to know the players and experiment with different systems and this match will provide further opportunity for the team to develop.
“Our Nations League campaign will be in full swing when we play Portugal and it can only be a huge incentive to the players to have the opportunity to test themselves against some of the best in the world.”
- ^ has confirmed (www.scottishfa.co.uk)
- ^ had one free fixture date (www.bbc.co.uk)
- ^ beat Hungary (www.bbc.co.uk)
- ^ losing to Costa Rica (www.bbc.co.uk)