Ryan Hardie came back to haunt St Mirren as he netted twice to put a major dent in Saints' survival bid.
Hardie spent an unsuccessful loan spell in Paisley in the first half of the season and he put his old club to the sword by coming off the bench to bag a late brace in a 2-0 win for Raith Rovers at Stark's Park.
It was John Hughes' first win as Rovers boss and the Kirkcaldy side's first in the Championship since October.
Jack Ross' Saints failed to live up to recent performances in a lacklustre display and the result is blow to their hopes of avoiding the drop, the Buddies are five points adrift at the bottom of the table.
Ross made one change to the side which was lauded for their display in a 4-1 defeat at Celtic Park. Adam Eckersley returned from injury to replace Gary Irvine.
During a scrappy opening to the game neither side were able to find any fluency and the high tempo that had been evident in Buddies' last few games wasn't there.
After 26 minutes Saints had their first sight of goal. John Sutton headed a long ball down for Cammy Smith, the pair then played a one-two to set Smith up for a strike at goal but through a ruck of Raith defenders it was blocked and cleared.
Lewis Morgan was next to try his luck from a Stevie Mallan short corner. He shifted the ball onto his left foot and from 20 yards his strike looked like it would trouble Raith's debutant goalkeeper Pavol Penksa but Iain Davidson was on hand to clear just yards from the goalline.
Morgan went close again seven minutes before the break with Smith once again the creator, taking Sutton's knock into the box and squaring for the winger, Morgan took a touch but dragged his shit wide from 10 yards.
The Buddies started the second half on the front foot and the impressive Smith threatened again with a neat shot on the turn from 18 yards but Penksa held well.
After 58 minutes Harry Davis took down a Mallan free kick brilliantly in the box, but he wasn't able to adjust his body in time to control the shot and he fired over the crossbar.
The Kirkcaldy side responded when Kyle Benedictus gave Stelios the slip on the left wing, his square ball was begging to be tapped in. But there was no takers for the home side, the ball spun up as a host of players attacked it and it fell to Declan McManus who could only head over.
The away fans were soon out their seats screaming for a penalty. Smith square ball appeared to bounce off a Raith hand and the Saints bench and players shouted for a spot kick in unison but referee Crawford Allan wasn't interested.
With 16 minutes the sting in the tail came for Saints. Davison crossed for Hardie and facing away from goal he flicked his head back and glanced into the far corner.
Barely five minutes later and disaster struck for St Mirren goalkeeper Billy O'Brien. He had the ball in his hands and inexplicably threw it straight at Hardie, the striker was able to control and then had the easiest of tasks to round the O'Brien and sidefoot into an empty net.