Nathaniel Atkinson scored a stunning volley with virtually the last kick of the game to salvage a point for Hearts in an enthralling Rugby Park encounter with Kilmarnock.
After a first half laden with missed chances, Chris Stokes and Kyle Lafferty gave the hosts a two-goal lead, the second goal coming from a stumble from goalkeeper Craig Gordon.
Stephen Humphrys fired in his first Hearts goal before Atkinson came to the rescue for Robbie Neilson's side deep into stoppage time.
Despite both sides playing midweek, they showed little sign of fatigue as play roared from end to end in the driving Ayrshire rain.
The first half came to a close with a Kilmarnock penalty claim waved away as Blair Alston fell under pressure from Alex Cochrane, who had hands on the midfielder.
It began with Hearts winger Barrie McKay inexplicably ballooning a shot over an open goal after a smart square pass from Lawrence Shankland.
In between those incidents Danny Armstrong, who scored a brace in the win over St Johnstone on Wednesday, nodded wide for the home side, while Shankland and Humphrys squandered openings for the visitors, who were looking to bounce back from their midweek European chastening at the hands of Fiorentina.
Alston and Alan Power had shots from inside the area blocked, while Robert Snodgrass saw his venomous free-kick caught by home keeper Zach Hemming.
The second half was every bit as breathless, with the added bonus of four goals.
Stokes met an enticing Armstrong corner just minutes after the restart to nudge the home side in front from close range.
While Gordon complained he had been impeded for the opener, Scotland's number one was badly at fault for Killie's second.
The Tynecastle skipper hesitated then stumbled at a backpass, allowing Lafferty to capitalise and force the ball in.
Hearts responded almost immediately as Humphrys raced onto a Snodgrass ball over the top and rounded Hemming to squeeze in a shot with half an hour remaining.
It looked like the visitors had run out of steam but, with mere seconds left on the clock, right-back Atkinson thumped in a lovely, left-footed volley that dipped perfectly into the bottom right corner as Killie failed to clear a deep free-kick.
The wide man followed up his midweek double as he turned provider for Stokes' opener and was a nuisance to the Hearts defenders throughout
The late equaliser will hurt but Derek McInnes' side appear to have found their bearings in the Premiership after a shaky start to their return to the top flight.
Attacking threats Armstrong and Jordan Jones haven't featured much so far this season but both are hitting form at the right time.
At the back, Killie look steadier, with Stokes and Ash Taylor forming a formidable partnership.
For Hearts, their usual mainstay of Gordon between the sticks looked uncharacteristically unsettled. The swirling wind and heavy rain can't have helped but for such an experienced operator he looked uneasy.
Despite the strength of their attacking options, Hearts wasted good chances in the first 45 minutes before coming up with two excellent goals.
Kilmarnock manager Derek McInnes: "It's a sore one any time you lose an injury-time equaliser. We give away a cheap free-kick and it allows them to put that one last ball in.
"Five minutes of injury time - I was a wee bit surprised at that but, still, you've got to see the game out."
Hearts manager Robbie Neilson: "We had a couple of opportunities early in the game that we probably should've scored from. If we score then, it's a different game.
"We lost a couple of poor goals - a set play and then and individual error. The pleasing thing is we managed to fight back an managed to get a point."
Kilmarnock are away to St Mirren on Saturday 15 October (15:00 BST), while Hearts travel to Italy to face Fiorentina on Thursday 13 October (17:45 BST) and face Aberdeen away on Sunday 16 October (15:00 BST)