St Johnstone won this Tayside derby to keep alive their slim promotion hopes.
The Saints won a couple of corners in the opening 10 minutes, but these were easily dealt with by the Dundee defence.
Dundee were dealt a massive blow after 18 minutes when Lee Wilkie was carried off just three games into his comeback from a serious injury.
Jason Scotland raced into the Dundee box midway through the first half but fired well wide of the target when he should have done better.
With half an hour played, Kelvin Jack saved the home team when he dived low to his right to deny Martin Hardie from close range.
On the stroke of half-time Jack made an excellent double save to deny Scotland and Martin Hardie from the rebound.
Jack went from hero to villain when he gifted St Johnstone the lead after 53 minutes. He was under very little pressure when attempting to catch John Henry's corner in front of goal, but he somehow made a real hash of it and ended up in the back of the net with the ball.
Hardie headed just over the crossbar for the Saints midway through the second half and with five minutes to go Kevin Rutkiewicz had a chance to double the lead, but from Paul Sheerin's left-wing cross the defender was well off target.