Stevie May scored twice as St Johnstone beat Aberdeen 2-1 at Ibrox on Sunday to reach the Scottish Cup final for the first time in their history.
The Dons were chasing a cup double after winning the League Cup last month and went ahead early on with a Niall McGinn goal.
May equalised just after the hour mark and smashed a low shot past Jamie Langfield with only six minutes left to set up a Celtic Park meeting with Dundee United on May 17.