The 25-year-old flapped at a corner from Mark Sideserf and succeeded only in helping the ball into his own net.
The hapless goalkeeper looked as if he wanted the Newlandsfield Park pitch to open up and swallow him while the goalscorer was swamped by his widly celebrating team-mates.
Sideserf said: "We don't want to let go of this cup and I think that really showed in our performance.
"It's maybe not the best goal I've ever scored, but it certainly goes down as one of the most important.
"That's me now scored four times in our last three games since moving over to the right wing, and all the credit must go to boss Tony McInally.
"He's an outstanding tactician and always likely to come up with little tweaks to improve the team.
"Before the game he told us we would get joy from dropping any corner kicks on top of the Pollok goalkeeper and his plan worked a treat – it was a case of better late than never."
Shotts had done their homework when it came to set-pieces, but otherwise they posed little scoring threat in this keenly-contested cup-tie which was watched by a bumper crowd of nearly 1000 fans.
It was the home side who came closest to breaking the deadlock after 25 minutes when visiting goalkeeper Johnny Murdoch did well to beat away a piledriver from Ross Hepburn.
The Lanarkshire side had to rely on their shotstopper again early in the second half when he used his feet to block a Brian McGinty shot after the Pollok midfielder had cleverly worked an opening for himself.
But, other than these half-chances, Pollok were equally devoid of attacking options thanks in no small part to Shotts choosing to deploy Paul Finnigan to man-mark Lok dangerman Carlo Monti – a battle that the experienced defender won hands down.
The cup holders received a boost with 25 minutes to play when their opponents were reduced to ten men after Steff Reilly picked up his second yellow card of the game after tripping Andy Scott.
McInally urged his troops forward and their enterprise paid off big time with a match-winning goal just two minutes from time.
It was a hard blow to take for the home side and manager John Richardson could not hide his obvious disappointment. He said: "Games can be won by a flash of genius or by a mistake and Saturday was definitely a case of the latter.
"I felt it was a horrible game decided by a horrible bloomer from Stevie. The worst thing of all was it came so late in the game that we had no way to come back from it."
Shotts boss McInally was understandably delighted given his preparations for the game had included a Saturday-morning visit to Hampden Park to try and have match bans imposed on Paul Burns and Allan McKenzie overturned on a technicality.
That bid failed, forcing the Shotts manager to make some last-minute changes to his game strategy.
He said: "It was a huge blow to our team plans, but both Paul and Alan showed great encouragement to the other players."