Midfielder Andy Dorman rescued a replay for the Buddies in a tie that St Johnstone will feel they should have won.
McDiarmid Park played host to an illustrious guest with UEFA president Michel Platini in attendance. The former Juventus maestro is no doubt more accustomed to slightly more glamorous events, but the atmosphere in windswept Perth should have made for an enjoyable experience for the French legend.
The St Mirren fans had made the journey north in vast numbers as over 2,000 Buddies supporters filled the away section.
Both sets of fans were in good voice, but it was only the home supporters who had anything to cheer in the first half as St Johnstone, assisted by a fierce wind, threatened to blow their SPL opponents away.
The hosts almost broke the deadlock in the 14th minute as Kevin Rutkiewicz rose to head Liam Craig's corner inches over the bar.
Just as the game was beginning to settle, Goran Stanic was clipped in the box by the clumsy John Potter and referee Dougie McDonald correctly awarded a penalty to St Johnstone. Liam Craig stepped up to calmly convert the spot-kick, sending Chris Smith the wrong way.
The first division side almost doubled their advantage two minutes later as Peter MacDonald ran on to Alan Main's clearance and his left-foot shot was smartly parried by Smith.
As half-time approached, a rainbow was visible in the distance and at the break it was St Johnstone who seemed destined for the semi-finals and the pot of gold that would accompany it.
The visitors continued to struggle in the second-half and the impressive Andy Jackson almost added a second goal for the dominant Perth side in the 70th minute, but his header was cleared off the line.
However, St Johnstone were punished for their failure to kill off the Love Street men in the 73rd minute when Dorman snatched the equaliser.
Substitute Stewart Keen flipped the ball on and Dorman raced clear of the home defence, before delicately lofting the ball over Main and into the net to send the vociferous travelling support wild.
Home manager Derek McInnes threw on the gargantuan Kevin James in the closing stages in an attempt to grab a late and deserved winner, but the Buddies held on bravely for a draw.