Hearts slipped a step closer to the relegation trapdoor after a second-half collapse at Kilmarnock.
The Tynecastle side started well, with Ryan Stevenson firing a 20-yard strike just over the top after two minutes.
At the other end, Jamie MacDonald had to act smartly in 17 minutes to claw out a close-range effort from Killie centre-back Lee Ashcroft after the Hearts defence failed to deal with a dangerous inswinging free-kick from David Moberg Karlsson.
Stevenson then fired a powerful strike just past from outside the box after playing a clever one-two with Dale Carrick in 22 minutes.
Hearts had a golden chance in 25 minutes when Kevin McHattie’s corner picked out Jordan McGhee unmarked at the back post but the defender headed wide from eight yards.
But just 30 seconds the Tynecastle side fell behind when Rory McKenzie burst up the right flank and saw his powerful cut-back inadvertently knocked into his own net by the unfortunate Hearts captain, Danny Wilson.
Hearts tried to respond immediately but Jamie Hamill lashed a low shot just past after being teed up by Carrick on the edge of the box.
The Edinburgh side deservedly drew level after half an hour when Carrick beat Killie keeper Craig Samson to a Callum Paterson through ball and dinked it into the net from just inside the box.
At the other end, Kris Boyd curled a free-kick over the top two minutes before the break.
Hearts threatened two minutes into the second half but Hamill shot over after being set up by Nicholson on the edge of the area.
But Killie restored their lead in 49 minutes when Kris Boyd forced his way into the box, held off Hamill, and slotted beyond MacDonald from around six yards out.
A Gardyne cross from the left then flashed across the face of the Hearts goal.
And Hearts fell further behind in 51 minutes when Boyd blasted home at the second attempt after a McKenzie cutback from the left found him on the edge of the six-yard box.
The Jambos pulled one back in 68 minutes when Nicholson slotted home a Billy King cross.
But Killie restored their two-goal advantage in 72 minutes when Gardyne, who had cracked a shot off the bar moments earlier, shot home after being picked out by a cross from Jeroen Tesselaar.