Former Walsall keeper Mark Gillespie made only his second appearance, while defender Christian Mbulu was given a first-team debut.

However, as it turned out the most influential change was the tactical one of bringing in Johnson to partner Curtis Main in attack.

Aberdeen, though, were not without their own injury worries with Mikey Devlin's foot injury making him a doubt for next week's final. That forced Andy Considine to pair up with Scott McKenna at the heart of the Dons defence.

However, after a rather uneventful opening 25 minutes the Aberdeen rearguard was cruelly exposed.

Presented with the first corner of the match, and with their towering defenders in the home box, Niall McGinn called for a short corner before laying the ball back to the halfway line for lone defender Shay Logan.

When Johnson intercepted the pass he had only one thing on his mind as he held off Logan until turning the defender inside the box before driving the ball beyond Joe Lewis for a well-taken goal.

Four minutes later Gael Bigirimana's cheeky attempt with a low free-kick from 35 yards forced Lewis to push the ball round his post.

From Bigirimans's corner, Main's touch set up the ball two yards from goal where Johnson popped up to nod it over Lewis and double his and Motherwell's tally.

That forced a bit of a response from the Pittodrie side and six minutes from the break Max Lowe's well-driven shot from just outside the box produced a fine diving stop from Gillespie.

Much more was expected from the Dons in the second half but within 10 minutes the home side extended their lead and ensure it was a miserable afternoon for the 1,100 Aberdeen fans.

Johnson was again at the heart of it and when his cutback deflected off Main, the ball fell kindly for Turnbull who took a touch before drilling the ball into the corner of the net to claim his third goal from four games.

In a real off day, the Dons' only reply came in the final minute when Lewis Ferguson's 20-yard drive forced a rare save from Gillespie.

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