Saints moved into the second position in the table after this convincing win over visitors Airdrie United, albeit by a solitary goal.
The home side's first half form was a massive improvement from last week's poor showing in their defeat at Dingwall.
Saints' defence and midfield fended off everything Airdrie Utd tried, and in particular totally nullified the visitors' Brian McPhee who had scored twice in Airdrie's 4-0 demolition of Saints' Tayside rivals Dundee.
Saints went ahead through Jason Scotland, who played a one-two with Ryan Stevenson just on the edge of the Airdrie penalty box before side-footing the ball into the net from 12 yards.
How this lack-lustre Airdrie outfit managed to fire home four against the Dee last week was taking on the air of a mystery.
Their first shot on target came with 62 minutes on the clock. McPhee set up Stephen McKeown, but Saints' keeper Kevin Cuthbert, called into action for the first time in the game, was equal to the task, thwarting the midfielder.
Scotland had two more cracking shots in the second period, but Airdrie's goalkeeper, former St Johnstone squad player Stephen Robertson, held the Trinidadian striker at bay.
Airdrie pressed forward in the second half, but the Saints' defence held firm.