A controversial Paul McGowan penalty 10 minutes from time helped St Mirren claim a 1-1 draw against ten men Celtic on Sunday.
Kris Commons had headed the Hoops into a sixth minute lead but St Mirren responded brightly and had an effort from Gary Teale disallowed in the 27th minute for a foul on keeper Fraser Forster.
The home side then felt they should have had a penalty in first half stoppage time when Georgios Samaras appeared to use his arm to control Teale's corner in the box.
Celtic lost goalscorer Commons to injury before they were reduced to ten-men in the 55th minute when Kenyan international Victor Wanyama saw a straight red for a clumsy high challenge on McGowan.
Time looked to be running out for St Mirren, who hadn't scored against the Hoops in the league in over 13 hours of play, before they were awarded an 81st minute penalty although Emilio Izaguirre's challenge on Esmael Goncalves appeared to be outside the box.
McGowan drilled the ball past Forster to continue the party atmosphere for St Mirren, who are still celebrating their League Cup win, as Celtic failed to secure a win for their third straight away match.
Celtic could still clinch the Scottish Premier League title next Saturday with a win at home to Hibernian if Motherwell lose their match against St Mirren.
The Hoops took an early lead with a superb header from Commons. Efe Ambrose swung a ball in from the right and Commons, one of the smallest men on the pitch, rose above Teale to bullet a header past Craig Samson from 10 yards.
The goal seemed to spur St Mirren into action with John McGinn releasing Paul Dummett down the left and the on-loan Newcastle United player's shot clipped the out rushing Fraser Forster on its way by the post.
Beram Kayal then nodded a Marc McAusland header off the line after he connected with a Gary Teale corner.
Steven Thompson then missed a great opportunity to haul St Mirren level when he got across Kelvin Wilson to meet a Teale cross from the right but the striker could only glance his header wide.
In the 27th minute St Mirren had the ball in the net when a cross from Teale floated into the top corner past Fraser Forster but referee Bobby Madden disallowed the goal for a soft foul on the keeper by Dummett.
Goalscorer Commons fired over from 20 before the Scotland international was stretchered off on the stroke of half time as a result of his own team-mate Kayal landing on his ankle.
The half ended in controversy as the home fans were screaming for a penalty when Samaras appeared to control a Teale corner with his upper arm. St Mirren players immediately surrounded ref Madden but he waved away their protests.
In the 55th minute Wanyama, who was just back from suspension, was shown a straight red card after a clumsy challenge on Paul McGowan.
With time running out St Mirren were awarded a controversial penalty as Goncalves went down under a challenge from Izaguirre on the edge of the box.
McGowan converted the spot kick as St Mirren managed to avoid defeat against the Hoops in a league match for the first time since March 2010.