Marius Zaliukas prodded home Hearts' extra-time winner to secure an astonishing Scottish Cup fifth-round comeback against St Johnstone.
Jamie Hamill's controversial stoppage-time penalty had levelled the scores in normal time at McDiarmid Park.
Murray Davidson's 83rd-minute goal had seemingly put the hosts on course for a place in the quarter-finals against St Mirren until that disputed penalty.
But Alan Maybury was ruled to have felled Suso to concede the spot-kick.
And, despite furious protests from Saints players accusing the Spaniard of a dive, Hamill ensured Hearts' survival into extra-time and ultimately on to a home tie in the last eight.
St Johnstone manager Steve Lomas had made four changes for the replay following Saturday's 5-1 thrashing by Dundee United.
It was no surprise that Alan Mannus replaced Peter Enckelman in goal, while Maybury, Murray Davidson and Frazer Wright started in place of Callum Davidson, Lee Croft and the suspended Dave MacKay.
And, in a bright start for the hosts, Cillian Sheridan lashed an effort just wide of the target.
Hearts, for whom David Obua and Scott Robinson returned in place of Ian Black and Andrew Driver, had a chance of their own when Danny Grainger fired a free-kick over the bar.
Visiting goalkeeper Jamie MacDonald was worked for the first time when he dived low to parry Sheridan's long-range drive, while Skacel's shot forced Mannus into an excellent stop.
Hearts began the second half by forcing a flurry of corners and almost grabbed the lead in fortuitous circumstances when Mehdi Taouil's stinging drive struck team-mate Zaliukas, but the ball drifted just past the post with Mannus beaten.
Chris Millar shot wide for the hosts, then his looping cross almost dipped underneath the bar.
Robinson blazed over when in a promising position, much to the dismay of the large travelling support, as both goalkeepers remained virtual spectators.
The home side finally broke the deadlock when Croft broke down the right and slipped the ball inside to Davidson, who prodded the ball high into the net.
Hearts substitute David Templeton weaved past three defenders but struck just inches wide of the post, while team-mate Adrian Mrowiec was denied by an excellent block by David McCracken.
The tiring visitors were handed a lifeline when referee Brian Winter ruled that Suso had been brought down by Maybury and Hamill sent Mannus the wrong way from the spot after furious protests from Maybury.
St Johnstone dominated the majority of extra-time, but Zaliukas prodded home with three minutes remaining after the hosts' defence failed to deal with Hamill's dangerous corner.
St Johnstone manager Steve Lomas: "I watched the DVD and feel it was a very, very soft penalty.
"I feel for my boys as I asked for a much-improved display after Saturday and they gave it everything. Sometimes you need a bit of luck in the Cup.
"I don't want to criticise the referee, but when you see the replay on television, he sees Alan Maybury and falls into him.
"We asked for a performance and felt we got that, but no matter what you do, you need a bit of luck.
"Ten seconds before the end, the referee gives a penalty. It's a massive call from him."
Hearts manager Paulo Sergio: "We can play better - and we should.
"But people forget that we are in a sequence of nine games in three weeks, playing every three days.
"The squad at the moment does not allow me to make the management I would like to do and the players are tired and we can feel that.
"But they were brave and we played with different kinds of strategies all the time and our players and our supporters deserve this moment.
"I should say that St Johnstone maybe deserve as much as us to go through as they too were playing three days after a bad defeat."