Aberdeen boss Derek McInnes is looking forward to taking on Saints, whom he managed for almost four years until leaving in October 2011.
Looking ahead to the semi-finals, the 42-year-old said: "St Johnstone is a club I know both as a player and manager.
"Watching them recently I can see they are going from strength-to-strength and when the game comes around it will be tough.
"And it was always going to be tough whoever we got, so we are delighted just to be in the draw.
"It's always a big moment playing a former club but a semi-final is a big occasion in itself and I hope we're in good form.
"But if we don't win it, then I would be pleased for St Johnstone to win."