Aberdeen 4-1 St Mirren

Aberdeen's Ryan Christie scored twice against St Mirren, the second a header from Shay Logan's cross

Aberdeen eased into the fifth round of the Scottish Cup with a comfortable win over Championship side St Mirren.

Adam Rooney opened the scoring for the home side from the penalty spot after Greg Stewart was brought down by Stelios Demetriou.

Ryan Christie added two more in the opening half, either side of Gavin Reilly's strike for the visitors.

Gary Mackay-Steven wrapped up the win with an outstanding effort just after the break.

St Mirren arrived in confident mood, riding high in the Championship and initially appeared intent on showing why.

They were quickly dismantled by an Aberdeen team that showed sharpness and desire after the winter break. The home side were dominant and ruthless.

Rooney neatly placed a penalty past St Mirren goalkeeper Craig Samson to break the deadlock after Demetriou upended Stewart. It was the start of a fairly miserable afternoon for the defender.

Stewart came close to a quick-fire second before the visitors showed they could carry a threat. Lewis Morgan danced into the box and fed Kyle Magennis, but his shot was well saved.

St Mirren striker Gavin Reilly pulled a goal back for the visitors with his 21st strike of the season

Aberdeen manager Derek McInnes is keen to add more silverware to the Pittodrie trophy cabinet and his players seemed equally eager throughout.

MacKay-Steven, who was in fine form, intelligently cut the ball back for the onrushing Christie, who side-footed a shot past two defenders and the helpless Samson. The defending was again inadequate.

At that point, it looked like St Mirren were facing a long afternoon. It did turn out that way, but they regained some short-lived hope when Morgan fired at Aberdeen goalkeeper Joe Lewis, who parried straight to the prolific Reilly.

The striker instinctively volleyed home to hand Jack Ross's side a lifeline.

Aberdeen winger Gary Mackay-Steven struck the goal of the game against St Mirren, lashing the ball into the top corner

It didn't last long, with Demetriou again glaringly at fault. The left-back's display was riddled with nerves. He had the chance to clear but headed straight off team-mate Ian McShane.

The ball fell for Shay Logan, who dinked a cross to the back post where Christie gleefully arrived to nod home his second.

Morgan came very close to reducing the deficit shortly after when a defensive mix up presented him with the chance to lob Lewis, but he was narrowly off target.

St Mirren had the chance to regroup during the interval and strategise how to cope better. Whatever they agreed was undermined immediately when MacKay-Steven thundered a wonderful shot into the top corner from the corner of the 18-yard box.

Niall McGinn made his first appearance since returning to Aberdeen, and almost scored against St Mirren

The tie was over, although Magennis should have done better from a great position but shanked wide. Aberdeen continued to press, too, and Stevie May should have converted Christie's chip across goal.

The home support enjoyed a thoroughly convincing performance and the substitute appearance of Niall McGinn, re-signed after a spell in South Korea. He nearly delivered spectacularly with a scissor kick which sliced inches past the post.

This was a professional job from the home side, with St Mirren facing an example of the standard they may encounter if they gain promotion to the Premiership.

Post-match reaction

Aberdeen manager Derek McInnes: "Very pleased. It was maybe seen as a [potential] upset, we were up against a good team in St Mirren, and we had to work hard for it. It wasn't all straightforward, there were moments of sloppiness in our game and we gave them some encouragement.

"I was disappointed with the goal that we lost, but we were very clinical in the first half. We scored some very good goals, I loved Christie's two finishes, and obviously Gary's finish is top drawer. Second-half, we were very experienced and saw the game out.

"We were always aware of the threat of St Mirren on the counter attack, you can see why they've been getting results in their own division. There's no doubt we were the better team in the 90 minutes.

"The intention is [to go all the way], there's no point going into a cup competition if you don't feel you can win it. There are a few teams who will be disappointed if they don't win it and there will be a lot of teams hoping to win it. We'd be one of the few teams disappointed if we don't win it."

St Mirren manager Jack Ross: "I was pleased with the first-half, we played well for long periods of that but we were punished for individual mistakes. Gary's goal after half-time is really quality and that kills the game. The latter part of the game I'm not bothered about because it was just making sure we were intact and we move on from it.

"The first-half is the part will be look back on most, because our shape was good but we learned that if you make individual mistakes then you will be punished.

"It's a good Aberdeen side with good individual players and they punished us for making mistakes. And we weren't as ruthless with opportunities in that period as well.

"We wanted to win and progress in the cup and it's a disappointed changing room because we're used to winning games, but our goal is to achieve promotion. Every time we've had a setback in the league we've responded really well and I'm sure the players will do the same.