A late Louis Moult goal saw Saints consigned to a narrow defeat against Dundee United at The SMiSA Stadium.
It was an afternoon of missed opportunities for Saints who passed up a number of big opportunities before seeing an injury-time penalty from Toyosi Olusanya saved by United goalkeeper Jack Walton.
There were three changes to the Saints side from last time out with Alex Iacovitti, Roland Idowu and Mikael Mandron coming in for Alex Gogic, Caolan Boyd-Munce and Olusanya.
The Buddies started brightly and came agonisingly close to opening the scoring inside four minutes when Richard Taylor leapt the highest to meet a corner but saw his header nodded off the line by Luca Stephenson.
Zach Hemming had to be alert to hold a powerful 20-yard strike from Kevin Holt, before Roland Idowu sliced a volley just wide of the far post three minutes later.
Saints looked the more likely in the opening 45 with Greg Kiltie forcing a save from Walton on 34 minutes. Idowu picked up the scraps, but his follow-up effort was blocked by the United defence. Walton pulled off another save in the final minutes of the first-half when he was at full stretch to push away a Killian Phillips header.
United thought they'd taken the lead two minutes after the restart when Vicko Sevelj tapped home a cross at the far post but the offside flag was raised and the decision was confirmed after a quick VAR check.
Two minutes later Elvis Bwomono had a huge opportunity to put Saints ahead when a brilliant Tanser cross looked primed to be knocked home, but the wing-back slipped and the ball trickled out of play.
It was then end-to-end stuff as the game approached the hour mark. Mandron was agonisingly close to putting us in front when his effort cannoned off the underside of the bar on 57 minutes. United immediately broke up the park with Marcus Fraser deflecting a Glenn Middleton strike off the Saints woodwork.
Saints should have taken the lead when Olusanya, a second-half substitute in place of Idowu, was sent scuttling clear by a lovely lifted ball from Mandron. The forward only had the goalkeeper to beat but his shot was saved by the feet of Walton as he looked to find the bottom corner of the net.
Hemming made a good stop to deny United substitute Jort van der Sande on 87 minutes before another brilliant save from the resulting corner.
But the Terrors would find a breakthrough when a long throw eventually found its way to Moult whose overhead kick found the net in the final minute of normal time.
Saints were presented with a glorious chance back into the match when referee David Dickinson awarded a penalty when Olusanya was felled by Holt. The forward stepped up to take but his tame effort was saved by Walton with the United defence reacting quickest to deal with the danger.
Full-Time: St Mirren 0-1 Dundee United
St Mirren: Hemming, Fraser, Iacovitti, Taylor, Bwomono (Penman 90), Phillips (Oseni 90), O'Hara (c), Tanser, Idowu (Olusanya 63), Mandron (Mooney 90), Kiltie (Boyd-Munce 73)
Subs Not Used: Urminsky, Gogic, John, Smyth
Dundee United: Walton, Adegboyega, Gallagher, Holt, Strain, Sevelj, Docherty (c), Ferry, Stephenson (van der Sande 86), Middleton (Moult 61), Dalby
Subs Not Used: Richards, Graham, Trapanovski, Fotheringham, Thomson, Cleall-Harding, Stirton
Referee: David Dickinson
Assistant Referee: Daniel McFarlane
Assistant Referee: Gordon Crawford
Fourth Official: Calum Scott
VAR: Alan Muir
Attendance: 7,440
