Sean Clare's stoppage time equaliser broke the hearts of all Saints fans this afternoon after a superb second half display against the visitors from Tynecastle.
A Stevie May brace either side and a third of the season for Ali McCann looked to have given Saints all three points before Clare equalised with a controversial goal in the 91st minute.
Liam Boyce and Steven Naismith were the others on target for Hearts.
An entertaining afternoon in football was in store for the 6000+ crowd at McDiarmid Park as Tommy Wright made five changes to the 0-3 defeat to Celtic in midweek.
January signing McCart replaced Callum Booth, Ralston came back in for Wallace Duffy, Holt was swapped for Liam Craig, and the front two of O'Halloran and Hendry became Chris Kane and Stevie May for the visit of Hearts.
Saints started the game well forcing some early pressure via corners that the Hearts rearguard were able to deal with relatively comfortably.
However, just after the 15th minute mark the large and rowdy travelling support were silenced as Saints took the lead.
Great work down the right-hand-side saw Chris Kane play Ali McCann through and he cut the ball back for Stevie May who cutely caressed the ball into the bottom corner past Pereira to make it 1-0.
The goal gave Saints a lift and Tommy Wright's men continued to push forward but while in the ascendency the visitors would nick and equaliser.
A lapse in concentration allowed Irving to slide the ball to Sibbick in the wide area and his low first-time cross was turned home by Liam Boyce to make it 1-1.
It got the away fans right into the swing and five minutes later the game turned on it's head as Hearts took the lead.
The Saints defence failed to probably deal with a Hearts corner and Souttar was able to hook the ball back towards the back post where Naismith was on hand to tap into an empty net making it 1-2.
It was end-to-end stuff as Saints came right back at their opponents, Pereira denying Ali McCann from equalising on 33 minutes.
Then it was Hearts' turn to attack with Toby Sibbick lashing an effort from the edge of the area narrowly wide of Zander Clark's post.
With five minutes remaining before the interval, Liam Gordon was forced off the pitch after a clash of heads of Liam Boyce. Boyce was okay to continue but Gordy was later stretchered and taken to hospital for further checks.
O'Halloran replaced the Saints defender and was on the pitch no more than a minute before picking up the first booking of the match as the sides went in at the break with Hearts in front.
Callum Booth replaced Scott Tanser at the break and whatever was said in the dressing room appeared to work as Tommy Wright's men came out the blocks flying.
Stevie May forced Pereira into action early in the second half before David Wotherspoon almost scored a pearler cutting onto his right foot and narrowly missing the Hearts 'keeper's top left corner.
On 52 minutes though, Saints would be level after a wonderful move down the left.
Callum Booth fed the ball to Wotherspoon who in turn found Craig before the midfield veteran turned the Hearts defence with a wonderful ball to Stevie May.
Mayzo turned provider this time, initially holding the ball for support, which came in the form of Ali McCann who composed himself with his first touch before lashing past Pereira to make it 2-2.
It almost got even better five minutes later as Saints continued to press and bombard a shaken Hearts side.
Anthony Ralston rattled the crossbar as his right footed effort looked destined for the net with Tommy Wright's men ramping up the pressure in search for a third.
And that would come from the spot after Halkett pulled down Jason Kerr in the box from a set piece.
The man tasked with putting the ball on the spot was Stevie May and he scored his second of the afternoon firing hard and straight down the middle to make it 3-2.
And Saints continued to push for more, with dazzling displays from the midfield trio of Craig, Wotherspoon and McCann along with the relentless pressure of the front pairing of May and Kane.
Kane came close again before McCann couldn't keep the follow up down as the home side looked more likely to make it 4-2 than concede.
On 88 minutes, just before coming off, Stevie May full of confidence tried an audacious effort from the halfway which looked goalbound before the back peddling Pereira managed to parry the ball away saving his blushes.
That was Mayzo's last action as he left the pitch a minute later to a standing ovation from the home fans with Deadline Day recruit Matt Butcher entering the field.
It would end in heartbreak for Saints though as Daniel Stendel's men snatched a point in stoppage time.
The ball appeared to come off Aidan White for a Saints throw-in on the halfway line but the linesman flagged instead for the visitors.
From the resulting throw, Naismith sent a long ball to Ikpeazu who clattered McCart but with the referee waving play on the ball broke to Sean Clare who struck a clean half volley straight into the bottom corner leaving Zander with no chance and the Saints fans and players distraught.
That's how it would end on an entertaining afternoon at McDiarmid but the performance should give Tommy Wright's men lots of confidence ahead of the midweek trip to Pittodrie on Wednesday.
MAN OF THE MATCH: Stevie May
SAINTS: Zander Clark, Jason Kerr (c), Liam Gordon (Michael O'Halloran 40), Jamie McCart, Anthony Ralston, Scott Tanser (Callum Booth 45), Liam Craig, Ali McCann, David Wotherspoon, Chris Kane, Stevie May (Matt Butcher 88)
UNUSED SUBS: Elliott Parish, Danny Swanson, Callum Hendry, Jason Holt
SCORERS: Stevie May (16 & 61), Ali McCann (51)
HEARTS: Joel Pereira, Sean Clare, Aidan White, John Souttar, Craig Halkett, Ewan Henderson (Donis Avdijaj 79), Andrew Irving, Toby Sibbick (Conor Washington 71), Ryotaro Meshino (Uche Ikpeazu 60), Steven Naismith (c), Liam Boyce
UNUSED SUBS: Bobby Zlamal, Oliver Bozanic, Clevid Dikamona, Lewis Moore
SCORERS: Liam Boyce (26), Steven Naismith (31), Sean Clare (90+1)
REFEREE: Greg Aitken
©Copyright 2016 - all rights reserved by St Johnstone Football Club
Registered in Scotland 7629
Unless otherwise stated all photographs on this site are ©Perthshire Picture Agency and may not be used without permission.