Highlights: Hibernian 2-2 St Johnstone
Jason Kerr scored an injury-time header to earn St Johnstone a Scottish Premiership draw at Easter Road.
Summer recruit Adam Jackson nodded Hibs into a 1-0 lead 25 minutes into a dull first half.
Michael O'Halloran smashed in a deserved equaliser, only for Florian Kamberi to strike back with a clever flick just 60 seconds later.
But Kerr's finish from six yards, following a Danny Swanson cross, would deny the hosts at the death.
Heckingbottom's tinkering angers Hibs fans
When Kamberi was named as the lone striker for Hibs against Morton last weekend, fans bemoaned the decision to start just one striker against a team from the Championship. Despite no shortage of goals in that game with Hibs winning 5-3, Heckingbottom gave the Easter Road faithful exactly what they wanted, naming Kamberi alongside summer signing Christian Doidge.
"They've been working hard together in training," said Heckingbottom before the match, and that was evident in the opening stages as Doidge stole the ball from Liam Gordon and squared it to Kamberi, whose effort cannoned back off the post and on to Doidge, who could not tuck away the rebound.
That was as good as it got for them as a pairing, with Hibs' first goal coming from a set-piece. Stevie Mallan's delivery landing right on the head of Jackson, who simply stood still and directed the ball past Zander Clark for his first goal since joining from Barnsley.
Doidge had a great chance to double the lead on the hour mark, with Scott Allan playing a lovely through-ball into his stride, but his effort was tame and easily dealt with by Clark.
That was the former Forest Green man's last involvement as he was replaced by Vykintas Slivka, moments after Heckingbottom felt the full frustration of the crowd when he brought Allan off for Daryl Horgan. The midfielder was not at his best but had been deployed wide on the right and should have had an assist from Doidge's chance just moments before.
Things then went from bad to worse for the hosts as St Johnstone worked a short corner into the path of O'Halloran in the box. He looked up as if to cross the ball, tricking Ofir Marciano into leaving his line, before hammering the ball in at the near post.
With pressure and frustration growing, Heckingbottom was given the perfect remedy - a goal from Kamberi, who finished neatly with a back-heel inside the box - less than a minute after they had conceded the equaliser.
Kamberi was the main bright spark for Hibs, and Heckingbottom will be eager to keep him at Easter Road beyond the end of the transfer window, with a move back to Switzerland rumoured to be on the cards.
But St Johnstone kept knocking on the door and despite leaving a few gaps at the back as they pushed for an equaliser, always looked like they were still in the game.
Deep into four minutes of stoppage time, Swanson picked up the ball on the left and curled in a beautiful in-swinging cross which was met firmly by the head of Kerr. The Saints captain knocked the ball back across goal and into the far corner, prompting ecstatic scenes in the away end.
The managers' reactions told the story - Tommy Wright's outpouring of relief after a poor start to the season was reflected in his animated celebrations, while Heckingbottom headed straight down the tunnel on the final whistle.

Man of the Match - Florian Kamberi
BBC Scotland's John Barnes at Easter Road
Florian Kamberi was my man of the match. He was the most creative of the Hibs players, particularly in the first half when he dropped short from his main striker's role to link with his midfielders. His touch and control interspersed with flicks caught the eye. He was also fouled in an advanced area for the free-kick which led to the Hibs first goal. Then to seal a top performance he scored Hibs' second with the deftest of flicks from six yards.
Saints Scott Tanser was a contender as well. He may have been playing left-back but he is always keen to push forward and on one occasion we even saw him pop up in the right wing position as he tried to create a chance for his team.
Normally Scott Allan would be in the reckoning for man of the match but we only saw an hour of him before he was replaced by Darryl Horgan but the creative midfielder was wasted in a wide right position. The home supporters let their manager know they were not happy to see their star man substituted.
'We deserved to win' - reaction
Hibernian manager Paul Heckingbottom: "It's a sickener: the nature of it. One's the last kick of the game and offside and the other is we've lost a runner and made a mistake. It feels like a defeat.
"The goals we conceded there are tough to take. It's clearly offside."
St Johnstone manager Tommy Wright: ""I enjoyed the overall performance, I thought we were the dominant team."
"A point was the least we deserved, in fact, there's no question we should have got all three points."