Alex McLeish said Manchester United midfielder Scott McTominay will be in Scotland's squad for the friendly against Costa Rica at Hampden Park on March 23.
McTominay, 21, made the decision last week to choose to represent Scotland at the international level despite being born in England.
"He will be in the squad," McLeish said, told Sky Sports. "I don't think that's the world's best kept secret at this particular moment.
"Scott was very receptive. I looked him in the eye and he gave me passion about playing for Scotland. I saw the passion and I really felt that we had nailed it that day.
"Of course he has to play a competitive game but if we can get him playing in the friendlies, he can see what it's all about.
"We can hopefully have some good performances. Obviously winning is the big thing and then Scott can be a part of it.
"He's had some great games with Jose Mourinho at Manchester United. He's only 21, he's not got all the answers -- I'm 59, at my last count, and I've not got all the answers but hopefully he'll get more right than wrong."
The midfielder, who qualifies for Scotland through his grandparents, did not represent either nation at youth level and would still be eligible to play for England as the game against Costa Rica is not a competitive fixture.
He has made 16 appearances in all competitions, including 10 starts, for United this season.