Ten-man Hearts dropped three crucial points in the race for the Scottish Premiership title with a gut-wrenching 1-0 late defeat at St Mirren in Paisley.
The league leaders played for more than an hour with one fewer player after Craig Halkett's first-half red card and survived a barrage of attacks until Miguel Freckleton's emphatic 88th-minute winner.
The Jambos remain six points clear at the top but have handed chasers Celtic and Rangers the opportunity to close the gap on Wednesday.
Stephen Robinson's much-improved St Mirren earned a much-needed first league victory in eight matches, taking them 12 points clear of bottom spot as they move above Dundee into ninth.
Ultimately, the hosts deserved the win. They were still the better of the two sides even prior to Halkett's dismissal.
But that's where early pressure turned into an onslaught.
The stand-in captain initially covered well for his defensive partner Stuart Findlay's mistake but then stumbled in possession himself before bringing down Jacob Devaney on the edge of the area to deny a clear goal-scoring opportunity.
And the first half drama didn't stop there.
St Mirren captain Marcus Fraser had the ball in the back of the net, however, team-mate Alex Gogic was adjudged to be in an offside position when he headed the ball off the post to tee up Fraser's rebound.
Robinson's side then thought they had a penalty when referee Steven McLean pointed to the spot following Harry Milne's challenge on Jayden Richardson, but the decision was factually overturned by VAR as the foul took place outside of the penalty area.
Hearts stopper Aexander Schwolow was called into action again early in the second period as he produced an outstanding save with his right shoulder from close-range to deny Mikael Mandron.
The visitors had seemingly weathered the storm thereafter but were unable to replicate the heroics of last month's back-to-back victories with a numerical disadvantage as Freckleton won it for the Buddies with a thunderous header from Declan John's corner two minutes from time.
Hearts may be just three points clear when they take on city rivals Hibernian next week. That's followed by a top-of-the-table clash with title rivals Rangers on Sunday 15 February.