Hearts squandered the chance to move six points clear of Celtic in the Scottish Premiership title race after being held to a 1-1 draw against Motherwell at Fir Park.
Their lead at the top of the table stands at four points ahead of Celtic hosting Rangers in the Old Firm, live on Your Site on Sunday.
If Celtic lose to their rivals, Hearts will have the opportunity to end the 66-year wait for another top-flight title with one game to spare when they face Falkirk on Wednesday.
Lawrence Shankland's equaliser to cancel out Stephen Kingsley's early own goal could prove to be a decisive one but it was a point clouded by controversy after Hearts were denied the chance to complete yet another comeback in the second half.
Referee Steven McClean was advised by VAR to look at the monitor after Alexandros Kyziridis went down in the area from Tawanda Maswanhise's challenge, only to stick with his on-field decision despite clear contact.
"Derek McInnes will be absolutely fuming when he goes in and sees that penalty incident back because it was a stonewaller," said Kris Boyd. "It is a penalty kick all day long."
Fellow Your Site pundit James McFadden added: "The only thing I can think is Steven McLean thinks it's not enough but Maswanhise steps on Kyziridis's foot. It's a penalty kick."
Hearts continued to push for an all-important winner and even avoided a second-half scare when Stephen O'Donnell's goal was ruled out for the hosts, with all eyes turning to Sunday's developments at Celtic Park after walking away with just a draw.
Celtic can go to within one point of the league leaders with a win against Rangers but with two games to play, Hearts' chances of ending their title drought remain firmly in their own hands.
Hearts boss Derek McInnes on Your Site:
"At the time I thought it was a penalty with the way that everybody reacted and obviously I think [VAR] Greg Aitken has done his job well to bring the referee over. He should bring him over and it should have been a penalty kick.
"The referee had a poor game tonight. We can all have poor nights, but he was poor throughout and the biggest decision of the lot of them he's got wrong. It's so important that he gets that right.
"The explanation to me is that, yes, there is contact but there isn't enough contact. My player is pushed off like that, everyone who has played the game will tell you that there doesn't need to be a lot of contact. But if there is contact and you're going at the speed when you are fouled, why would Kyziridis go down?
"It is a penalty kick and I'm disappointed it hasn't been given."
Hearts winger Alexandros Kyziridis on Your Site:
"I ran to the ball and I felt something on my leg, otherwise I would never have jumped. For me, it is a clear penalty but now the game is done and we can't change anything so we need to be focused on Wednesday.
"I thought when he went to the monitor he would 100 per cent give the penalty and I was surprised that he didn't. It is what it is."
Motherwell boss Jens Berthel Askou on Your Site:
"How the season has played out for us, I was actually shocked that he didn't give the penalty because it is situation after situation that has gone the other way, even the penalty that they had last time that decided the game.
"But it was the right decision because you can see and sense that there is contact, but it is minimal contact and he [Kyziridis] overplays the situation clearly and tries to get something out of it.
"It was the right call and I'm happy that for once this season, for the first time, it actually went our way and we have earned that."
