A deadly concoction of potent finishing and lethal defending conspired to swiftly kill off Dunfermline in a truly grim first half for the Fife club as St Mirren claimed a convincing 4-0 victory to march into the Petrofac Training Cup semi-finals.

The East End Parkers have been riding high in the Ladbrokes League One table, with last week’s 3-0 win over Albion Rovers keeping within one point of leaders Ayr United. However, their recent form on league duty spectacularly failed to transfer over to their cup quest in Paisley yesterday, with three first half goals realistically destroying any chance of being the next team to add to St Mirren’s shaky start to the season.

“It’s hard to pinpoint but obviously defensively we can’t afford to lose the goals that we did,” said Allan Johnston, the Dunfermline manager. “Overall I don’t think anyone played well. At times you get the odd occasion when one or two don’t play well but I think the majority of them didn’t play well.

“It was just a bad performance.”

Within 10 minutes his team were behind. A Sean Kelly through pass down the left caught out full-back Shaun Rooney as Cameron Howieson latched on to the ball and swung it into the box before vanishing head first over the advertising boards. The cross found Calum Gallagher unmarked seven yards out for him to calmly volley into the net. A St Mirren scouting party was soon sent to fetch Howieson from three streets away.

The second arrived midway through the half, this time Gallagher turning provider. The purple vision that was Ben-Richards Everton slipped near the edge of his own box, allowing the St Mirren forward to pounce and drive into the box. The former Rangers man then showed the vision to look up and square to the inrushing Stephen Mallan to drill a lot shot under Sean Murdoch.

By the time Scot Agnew ghosted into the box to despatch a similar shot from Keith Watson’s cross eight minutes before the break, it was already goodnight Dunfermline. The fact Mallan grabbed his second two minutes before the end of the game was somewhat of an irrelevance.

It was sad indictment of the East End Park club’s play that the best opportunity that came their way was inadvertently cleared by their own player. With the game still within reach at 2-0 – sort of - Rooney’s cross-cum-shot was diverted away from the back of the net by Joe Cardle and over the gaping goal and into the aghast 800 Dunfermline supporters behind it. Woops.

“We started the game exceptionally well,” said Ian Murray, the St Mirren manager. “We are delighted to get into the areas of the park to exploit them and secondly when we did we showed really good quality. We will try and take that into our league form now.

“It was a potential banana skin with folk looking at our home form and Dunfermline doing really well in the league. We knew if we dropped our levels at any point in the gamer they would come at us, so it was important to start the game well.”