Scotland earned a superb 1-0 victory away in Croatia before falling to a narrow 3-2 defeat to England at Wembley last month, and the former Southampton boss has insisted that he would be disappointed if his side can't continue their recent run.
The 56-year-old told reporters: "It would be disappointing if we can't keep it. I've got a vision of how I want us to play, and the players know that.
"If the players keep to that, and do the right things and concentrate, then the result will take care of itself."
Scotland are currently in fifth position in Group A, but three points on Friday could see them move as high as third.