Kilmarnock struck in both halves to see off League 1 Cove Rangers and progress to the Scottish Cup quarter-finals.
Marley Watkins' second goal in four days broke the visitors' resolve when he stayed alert to flick home from a corner.
It was far from a comfortable afternoon for the Premiership high fliers, but they sealed their spot in the last eight when Danny Armstrong rifled the ball beyond Nick Suman.
Derek McInnes' side will learn who face for a trip to Hampden in Sunday's draw, which is live on BBC One Scotland (16:30 GMT) ahead of Airdrieonians' tie with Hearts.
The best chances of the early stages came the way of the visitors, though Rumarn Burrell failed to punish his former side as he saw his volley cleared off the line by Stuart Findlay.
A restless home crowd was lifted when Kevin van Veen nearly opened his account on his first start for the Ayrshire club, his deft header looping onto the Cove crossbar.
While the Dutchman has dominated much of the talk around Kilmarnock since his deadline-day arrival, it was summer signing Watkins who again made the difference.
Going ahead late in the first half didn't do much to lift the hosts' level as they laboured for much of the tie and endured a few ropey moments against Paul Hartley's side.
But substitute Armstrong continued his fine campaign when he belted Rory McKenzie's corner into the back of the net to ensure Kilmarnock's name stays in the hat.
Kyle Vassell so nearly added extra gloss to the victory, denied by Suman charging back to claw the striker's lovely dink off the line.
Player of the match - Marley Watkins (Kilmarnock)
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