Eamonn Brophy had a mixed afternoon against former side Hamilton as he fired Kilmarnock ahead but then gifted the penalty that allowed Accies to claim a 1-1 draw.
Steve Clarke’s side were looking for the result at the Hope Stadium which would have moved them up to second spot.
But Brophy’s early opener was cancelled out by Mikel Miller’s spot-kick after the former Accies striker was penalised for a penalty box handball.
Killie now drop to fourth following their second stalemate of the campaign with Martin Canning’s team. The Accies boss will view it as a handy point gained but St Mirren’s win over Motherwell means the Lanarkshire outfit now sit just two points above the drop zone.
Brophy chose to quit Hamilton 18 months ago after struggling to break into Canning’s side, and the ill-feeling sparked by his exit was still evident as he received a round of boos from the home support as he celebrated his seventh-minute winner by running towards them cupping his ears.
Greg Taylor’s charge into the box drew Accies’ attention but they should have been watching Scotland Under-21 frontman Brophy, who collected Taylor’s pass before rifling into the far corner from a tight angle.
Brophy was looking dangerous again as he skipped past Lemmy Sowah out wide but strike partner Greg Stewart hooked the cut-back wide.
Accies keeper Gary Woods was then forced to parry Jordan Jones’ long-range strike while Imrie’s block rescued Sowah after the German’s mistake almost let in Stewart again.
Killie had been firmly on top for the first half hour but Accies gradually gained a foothold. Darian MacKinnon’s quick exchange with James Keatings saw the Accies enforcer burst into the box but his strike was straight at Daniel Bachmann while Aaron McGowan wasted another good opening soon after.
But the equaliser came nine minutes before the break as goal hero Brophy became the sinner when he handled a Keatings cross.
MacKinnon rammed the loose ball into the net just as referee Bobby Madden blew his whistle and pointed to the spot. The end result was the same in any case as Miller slotted home from 12 yards.
The hosts came close to taking the lead four minutes after the interval as Scott McMann slammed the ball off the base of the post after Miller’s run had cut Killie’s back-line apart.
Kilmarnock’s Gary Dicker was screaming for a penalty on the hour mark as he claimed Matt Kilgallon had used a hand to block his goal-bound header but Madden saw nothing wrong.
Brophy’s afternoon came to an end soon after as he was replaced by Kris Boyd and the veteran’s flick-on for Stewart should have resulted in Killie snatching the win with 14 minutes left, but the on-loan Birmingham ace wasted his one-on-one opportunity against Woods.
Both sides had chances to win it late on but neither Kilmarnock’s Scott Boyd nor Accies scorer Miller could take advantage.