Scotland will meet the Swiss on the back of Friday's 5-1 hammering by Germany in the Euros opener.
Swiss captain Granit Xhaka and Tierney were team-mates at Arsenal and the fullback said: "He's a good friend of mine and he helped a lot at Arsenal for the four years I was there.
"They've got quality players all over. They've been in major tournaments for years now, they've got far. They've got through the group so they've got the experience of doing it, so we're up against that as well.
"We want to be a lot more aggressive, we want to make it harder for everyone and not give people as much time on the ball.
"We know probably four points gets you through in a tournament like this. That's the aim, is to get through.
"We believe we can do it but we need to go and show it."