Danny Invincibile proved that Heart of Midlothian are anything but, as the Kilmarnock striker dented the Scottish Premier League title ambitions of Graham Rix's players in a torrid encounter at Rugby Park.
The Australian's goal at the start of the second half yesterday proved decisive for the side chasing a Uefa Cup place and provided a measure of revenge after being knocked out of the Scottish Cup by the second-placed team just a fortnight ago.
It was a bad day all round for Hearts. Neil McCann, who was returning to the club after an absence of seven years, found his debut abruptly halted after just 25 minutes when he was badly hurt by David Lilley's crude challenge.
McCann was part of the Hearts team that won the Scottish Cup in 1998 before earning the club a record £1.9 million from his sale to Rangers. A subsequent move to Southampton enriched his bank balance but not his soul and when he negotiated his release from St Mary's last week, the Scotland player eschewed Premiership offers from Wigan and Sunderland to continue his affair of the heart.
His departure was a shame for Hearts, because there was every indication that McCann had rediscovered his old zest, as he proved with one burst that left Lilley in his wake before crossing a low ball that Calum Elliot ought to have finished.
Michal Pospisil might also have scored for the visitors but his 19th-minute volley was kept out by a remarkable one-handed save from Alan Combe.
However, the contest then descended into rancour, littered with ugly challenges. Kilmarnock almost profited from Robbie Neilson's poorly-timed effort on Steven Naismith, as Garry Hay's curling free-kick was pushed over the bar by Craig Gordon eight minutes before the interval.
When the deadlock was finally broken, just 70 seconds into the second half, it had a stroke of fortune. Colin Nish's drive into the box was followed by a shot that was blocked by Andy Webster, but the ball broke into the path of the industrious Invincibile to steer his shot past Gordon to the crowd's delight.
The toll of fouls escalated but there was no shortage of excitement as Gary Wales passed up the chance to punish his former team after beating the offside trap, and then Elliot came close to equalising by bravely diving to meet James McAllister's free-kick only for his header to narrowly miss the target.
Wales and Neilson were then involved in a fractious clash before Hay was booked for his part in an ugly fracas after Elliot thumped into Combe.
As Hearts vainly pursued an equaliser, they left gaps at the back and Wales exposed that in the dying minutes as he escaped Neilson's stumble and cut the ball back for Nish, only for the striker to be denied by Gordon's incredible reaction save. Hearts, though, could not take advantage of that escape.