VAR threatened to deny St Mirren a deserved victory before super sub Alex Greive grabbed his side another clinical late winner.
The dominant Buddies hit the woodwork three times against Dundee United with Charles Dunne, Curtis Main and Jonah Ayunga all inches away from netting.
Main gave the hosts a first half lead with a close-range header before the Terrors equalised early in the second as substitute Steven Fletcher fired the visitors level.
VAR was always likely to make a big first appearance in Paisley and after an hour it denied Ayunga after the striker thought he'd doubled the Saints' lead, with Keanu Baccus pulled up for a foul in the build-up.
But just as he proved against Livingston at the start of the month, New Zealand international Greive climbed off the bench to produce a clinical finish and bag his side all three points.
The win, the Buddies' fifth in six home matches, lifts them up to joint-third in the Premiership table alongside Aberdeen.
The Buddies had to reshuffle their defence with Declan Gallagher and Scott Tanser both ruled out with injuries. Alex Gogic and Richard Tait stepped in to the back five in their place.
Jamie McGrath was back on his old stomping ground for the first time and the talented playmaker almost crafted his new team an opener inside the opening five minutes.
His fine delivery from a free-kick into the six-yard box caused chaos, with Richard Tait almost netting an own goal as he hacked clear. Luckily for him his keeper Trevor Carson was alert and cleared the ball to safety.
The game was an open affair from the kick-off. Jonah Ayunga saw a shot blocked for a corner after being set up cleverly by strike partner Curtis Main.
Ethan Erhahon picked out Charles Dunne from the resulting set piece, with the centre back rattling the bar with a powerful header.
The Buddies began to dominate proceedings as the first half progressed. Ryan Strain was proving a nuisance down the right wing, whipping a superb ball into the box which somehow cleared both Main in the middle and Ayunga at the back post with United keeper Carljohan Eriksson scrambling.
Erhahon was once again impressive in midfield. The midfielder produced a defence-splitting pass to release O'Hara on the left, who skipped past his marker before pulling a cross back into the box.
The ball fell to Keanu Baccus, who rifled a shot which was blocked before referee Grant Irvine spotted a foul by Curtis Main on Ryan Edwards just as Strain knocked into the net.
The Saints were knocking on the door, with Baccus' cutting through ball sending Ayunga tearing through on goal. United defender Liam Smith pulled off a superb block to deny the forward, who also rippled the side netting with another fierce effort just after.
The visitors started to settle into the match, with McGrath and full back Aziz Behich linking ominously down the left flank.
Carson almost gifted United an opener when he needlessly raced off his line, with Tony Watt's looping long range effort dropping just inches past the post to spare the keeper's blushes.
Five minutes before half-time St Mirren broke the deadlock. Wing back Richard Tait cut inside on his right foot before curling a fine cross to the back post, which Main guided goalwards. His effort hit the inside of the post before ricocheting in off keeper Eriksson.
Full of confidence, Main almost smashed in a memorable second with a tremendous left-footed effort from all of 30 yards that rattled the crossbar with Eriksson beaten.
Arnaud Djoum went into the book for a late challenge early in the second half after wiping out Baccus as the Aussie burst through the midfield.
United turned to Scotland international Steven Fletcher off the bench very early after the break as they looked to pose more of a threat up front.
Ayunga took it into his own hands to try and create the Buddies a second. He pressed the defence high before regaining possession, cutting inside and smashing a strike across goal that clattered the left hand post.
Less than a minute after going so close to doubling their lead, the Terrors fired themselves level. Watt cushioned a header down to Fletcher who showed all his experience to calmly net past a flat-footed Carson.
It took an hour for VAR to make its first big call in Paisley, but when it came it was a crucial one.
The Buddies thought they'd retaken the lead when Strain picked out Ayunga on the edge of the box, with the striker deftly curling into the bottom corner.
The celebrations were cut short though as Irvine was called over to the monitor in front of the Main Stand, with the whistler eventually ruling the strike out for a foul by Baccus in the build-up.
Fired up by the decision, Baccus blazed a strike agonisingly wide from the edge of the box as the Saints pressed for a goal VAR couldn't rule out.
Watt directed a header inches wide as the game continued to ebb and flow, with both sides hunting a late winner.
Robinson finally turned to his bench with 10 minutes left on the clock, New Zealand international striker Alex Greive replacing Ayunga up front.
Former St Mirren defender Smith fizzed an effort from distance that had Carson scrambling, with the ball flying just past the post.
Greive had only been on the park for four minutes but he made his mark to put his side back in front. Erhahon's sublime cross from the wing picked out the bustling forward who clinically directed his header into the bottom corner. No VAR was needed, with the home fans producing some ironic cheers when the restart was taken by United with the goal confirmed.
The Buddies had another chance to put the game to bed late on when O'Hara sent Greive through on goal. He teed up Main, who could only drag a shot straight at Eriksson.
And United almost levelled at the death when Scott McMann's late cross clipped the outside of the post, with Saints clinging on to all three points at the end of a thoroughly entertaining afternoon in Paisley.
READ MORE:
