Two sublime St Mirren strikes weren't enough to seal progression to the Scottish Cup semi-finals as Hearts edged a breathless tie.
More than 1,500 Saints fans made the trip through to Tynecastle and they certainly got value for money, if not the result they were hoping for.
In an end-to-end first half the Jambos fired themselves into a two-goal lead thanks to close-range finishes from Beni Baningime and Peter Haring.
The Buddies fought back before the break, with Eamonn Brophy netting superbly from Richard Tait's pinpoint cross to halve the deficit.
The Saints levelled in emphatic fashion when Connor Ronan picked the ball up around 25-yards from goal before unleashing a thunderbolt that fizzed past Craig Gordon and into the top corner.
While the Paisley side looked to push on, Hearts punished some slack defending when substitute Aaron McEneff found space in the box to guide an unorthodox finish past Jak Alnwick.
And Ellis Simms put the final nail in the coffin when he netted from close-range, ending St Mirren's Scottish Cup dream of a return to Hampden this season.
Stephen Robinson made just one change from Wednesday night's dramatic late win against Dundee, with number one keeper Jak Alnwick returning between the sticks after recovering from Covid-19.
Eamonn Brophy was charged with leading the line in the capital, with winger Jay Henderson forced to make do with a place among the substitutes despite his impressive impact at Dens Park.
Brophy was in the thick of the action within just two minutes, clashing heads with Hearts centre back Craig Halkett.
Both received treatment before continuing as the quarter-final literally started with a bang.
Brophy tested Craig Gordon's reflexes with an early sighter from the edge of the box after being teed up by Jordan Jones.
A minute later Alnwick was called into action for the first time, beating away Barrie McKay's powerful drive.
The opening fifteen minutes were edgy, with both sides sizing each other up and clearly keen to avoid losing an early goal.
Charles Dunne pulled off an important clearance on the six-yard line as a dangerous Liam Boyce cross whizzed into the box.
The relief was only short lived though as from the next attack Hearts broke the deadlock. McKay drove down the left wing before picking out striker Ellis Simms in the box.
Alnwick pulled off a superb initial close-range save from his shot, but with the ball bouncing around the six-yard box Baningime was on hand to slam in and open the scoring with his first goal for the Gorgie club.
The Buddies looked for an instant reaction and were screaming for a penalty when Scott Tanser's powerful long range shot looked to have hit a Hearts hand in the box.
The Jambos were still dominating proceedings though, with Ben Woodburn sliding Simms in on goal. His low strike fizzed well wide as the hosts looked to double their lead.
The Saints defence were struggling to keep up with the home side's pacey attacks and one soon turned into two.
Boyce found space in the middle of the park before slipping in Ben Woodburn on the right wing. His first time pass picked out Haring who slammed into the roof of the net from close range.
The Buddies looked to be on the ropes but out of nowhere they pulled one back.
Richard Tait found space on the right wing and he delivered a pinpoint cross that Brophy sensationally guided first time past Gordon and into the top corner.
The first half was turning into a superb spectacle, with Hearts inches away from restoring their two-goal advantage when Boyce's overhead kick was blocked only as far as Halkett. His drive thundered off the underside of the crossbar before eventually being cleared to safety as the home side took a 2-1 advantage into the break.
St Mirren returned unchanged from the break, with Brophy testing Gordon with a looping header shortly after the interval.
Alnwick produced a fine stop from Nathaniel Atkinson's powerful effort, before reacting very smartly to save Woodburn's deflected strike as the second half started at the same frenetic pace as the first.
Jones almost got on the end of an Alnwick long ball as the Hearts defence failed to clear the danger, with Gordon eventually clearing the ball away for a corner.
The Buddies were pressing hard for an equaliser and Gordon was called into action again to tip Greg Kiltie's header past the post.
The Paisley side deservedly equalised from the resulting set piece, finding the net in stunning fashion once again.
Boyce cleared away the set piece but only as far as Ronan, who unleashed a simply unstoppable 25-yard effort into the top corner past a flailing Gordon.
This rollercoaster of a game didn't stop there. Hearts substitute Aaron McEneff made an almost instant impact, cleverly directing Atkinson's cross past Alnwick just 60 seconds after taking to the field.
Haring blazed over the bar from an excellent position as the Jambos threatened to take the game away from the Saints.
Robinson threw caution to the wind as he sent on Jay Henderson and Alex Greive, with the Buddies desperate to find a leveller in the last quarter of an hour of the match.
Haring's header at the back post only just cleared the far post as St Mirren just managed to stay within striking distance of the home side.
Stephen Kingsley was next to threaten a fourth, with Alnwick tipping his goal-bound free-kick just by the post.
In the end it was Everton loanee Ellis Simms who put the tie to bed, netting from McEneff's pinpoint cross to send the Tynecastle side through to the semi-finals.
