Simo Valakari will have enjoyed his first stint on the bench as St Johnstone manager after Nicky Clark’s late strike sealed all three points for the visitors.
Simon Murray gave Dundee a first half lead after a bizarre defensive gaffe before substitute Graham Carey’s superb strike levelled things up.
A SIX MINUTE, 30 SECOND VAR review for the winning goal could only postpone the jubilant Perth celebrations at full time.
It is the first back-to-back league wins for St Johnstone in two years.
The team was unchanged from the side that beat Ross County 3-0 the previous weekend with Clark supporting the attacking partnership of Adama Sidibeh and Benji Kimpioka.
Midfielder Cammy MacPherson remained unavailable and striker Uche Ikpeazu also missed out as he continues his recovery to full fitness.
Valakari’s blueprint was noticeable from the start with Saints players attempting to pass out from the back through the Dundee press.
There was no goalmouth action to speak of before Saints fell behind in calamitous fashion on 12 minutes.
It looked for all the world that Jack Sanders would get to Dundee goalkeeper Trevor Carson’s long ball first as Saints shotstopper Ross Sinclair rushed off is line.
But up popped Simon Murray who nicked in first, poked the ball high into the air and awkwardly chested home leaving Sinclair and, in particular, Sanders red faced.
Sinclair somewhat redeemed himself just moments later, preventing a Dees second with his foot from a Ziyad Larkeche strike.
Sidibeh found himself clean through on 35 minutes but instead of picking his corner his attempt to round Carson was thwarted and his chance was gone. He should have buried it.
Saints didn’t want the half to end as their momentum was building. An attempted chip by Clark sailed over just before half time after good work down the right from Matt Smith and Kimpioka.
The ‘Simo Effect’ was clear in the opening 45 – his players had 73 per cent possession but nothing to show for it.
Playing towards the away fans, St Johnstone were on a mission at the restart.
Kimpioka’s stooped head was well parried by Carson, before Clark saw a shot blocked and Matt Smith headed the rebound wide.
Would it be one of those days?
From nowhere there were appeals for a handball on Smith who blocked Curtis Main’s goalbound shot. VAR was not interested.
Then it was substitute Graham Carey who provided the cutting edge and gave Saints the lead they richly deserved just after the hour mark.
The Irishman was left with both time and space outside the box before curling a fine strike into the bottom corner.
A couple minutes later Sidibeh couldn’t quite connect his header from Drey Wright’s deep cross.
Then Lewis Neilson should have given Saints the lead with minutes of normal time remaining. Sidibeh clipped in a delightful cross but he headed straight into the arms of a grateful Carson.
Dundee had a couple of attempts themselves that were both comfortably gathered by Sinclair in the Perth net.
But Saints would not be denied as Clark pounced when the clock struck 90 minutes. Carey’s corner caused chaos in the Dundee box before the veteran striker poked home from centimetres out.
The wild celebrations were halted by a VAR check for offside and a handball on Dundee’s Simon Murray in the box.
However, it was not possible to properly draw the lines for a potential offside against the St Johnstone goalscorer – so referee Kevin Clancy was called across to look at the angles himself.
Clark’s body was blocked by other players on the camera so they couldn’t get a body part clearly to accurately draw the line.
He agreed with the on-field call that it was onside. Had the goal been ruled out, St Johnstone would have had a penalty for handball against Simon Murray before Clark scrambled home.
Following a word with both managers Kevin Clancy pointed to the centre circle and sent the Perth support into the rafters once again.
It was no more than Saints deserved who climb into the top six.
LINE-UP: St Johnstone – Ross Sinclair, Andre Raymond (Kyle Cameron 58’), Jack Sanders, Lewis Neilson, Jason Holt, Nicky Clark, Drey Wright, Adama Sidibeh (Makenzie Kirk 88’), Matt Smith (Graham Carey 58’), Sven Sprangler, Benjamin Kimpioka.
Subs not used: Josh Rae, Aaron Essel, Max Kucheriavyi, Josh McPake, David Keltjens, Fran Franczak.
ATTENDANCE: 6548
REFEREE: Kevin Clancy
VAR: Nick Walsh