Watch SPL video highlights as St Johnstone stun Celtic in Perth
Goals from Gregory Tade and Rowan Vine gave Steve Lomas’ side their first league win of the season.
St Johnstone battled back from behind to earn their first SPL win of the campaign and move off the bottom of the table.
Kris Commons had given the Hoops the lead after three minutes but Saints equalised through Gregory Tade.
The Perth squad had been hit by a virus, forcing training on Thursday to be cancelled.
Murray Davidson only lasted 22 minutes before having to come off for Chris Millar.
But they showed their battling qualities and took all three points when Rowan Vine curled the ball past Fraser Forster.