Kris Boyd's first Clydesdale Bank Premier League goal in three years was not enough to secure Kilmarnock victory.
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Esmael Goncalves had struck first for St Mirren men but despite levelling through the former Rangers frontman, the hosts could not find a winner as they dropped two points to leave them sweating on a top-six place.
Killie must now beat Dundee at Rugby Park on Saturday in their final game before the SPL splits if they are to hold off Aberdeen and Dundee United and take their place in the upper half of the table.
Boyd's last goal in the SPL came on the final day of the 2009-10 season when he struck for champions Rangers in their 3-3 draw with Motherwell at Ibrox.
And the top-flight's record scorer showed he has lost none of his predatory instincts as he smashed home a leveller within two minutes of the start of the second half.
But there was controversy as the newly crowned Scottish Communities League Cup winners survived a late penalty call against last season's winners.
James Fowler burst through on goal but was barged into by David Van Zanten, only for referee Crawford Allan to wave play on.
Killie had been boosted ahead of kick-off with the news that striker Paul Heffernan had shaken off a groin injury to partner SPL record scorer Boyd up front.
But it was another one-time Ibrox attacker who wasted the first chance of the night when Steven Thompson blasted over as the hosts failed to clear from Gary Teale's second-minute corner.
Boyd was soon involved, though, playing in Fowler from a quick free-kick but his midfield colleague was tame with a shot straight at St Mirren goalkeeper Craig Samson, while the 18-cap former Scotland striker then headed over from Borja Perez's corner on 18 minutes.
Thompson came within an inch of connecting with Paul Dummett's low cross just before the half-hour mark after the on-loan Newcastle left-back fired a teasing cross into the six-yard box following a clever one-two with Goncalves, who then fired wide himself seconds later.
The action was open and sweeping from end to end but it was Killie who were caught out much too high up the pitch.
Boyd had chased a hopeful ball into the box from Ross Barbour but was beaten to it by the onrushing Samson. Within seconds the visitors had worked it to van Zanten and the Irishman produced a perfect through-ball in behind the Killie backline for Goncalves to burn past Mark O'Hara before slotting under Cammy Bell.
Two minutes before the interval, the on-loan Rio Ave frontman then muscled beyond Momo Sissoko to blast another attempt but this time Bell palmed it down before Goncalves pushed the rebound wide.
Saints' half-time lead was harsh on Kenny Shiels' men, but with 90 seconds of the restart they were level as Boyd struck.
Perez lofted a ball in behind the Paisley defence and Boyd was clinical as he connected well to send the ball past Samson at his near post and register his 165th goal in Scotland's top flight.
The provider of that chance volleyed fractionally wide on 63 minutes from Garry Hay's clipped cross while Boyd was denied a second when his header from Fowler's looping cross was stopped by Samson.
St Mirren had battled back from a goal down against Celtic on Sunday to grab a late equaliser but they looked a tired side in the closing stages as Killie piled forward.
They managed to drag themselves upfield, however, as Thompson teed up Teale with 10 minutes left - but the former Scotland cap could only flash a weary effort wide.
And the visitors looked out on their feet as Fowler burst into the box in the final minute before being bundled over by last-man van Zanten. It looked a certain penalty but Allan waved Killie claims away to leave them with all to play for against Dundee this weekend.