To round things off, striker Cosgrove struck again after 77 minutes from close range to ensure the Dons go into next Sunday's Scottish Cup semi-final with holders Celtic in fine spirits.

Aberdeen began brightly as Lewis Ferguson's fourth minute free-kick was deflected just over the bar to whet the appetite of the visiting fans behind the goal.

Dundee's John O'Sullivan then threatened with a cross for Craig Curran but Scott McKenna cleared the danger.

A few minutes later, Dundee midfielder Jesse Curran hit an ambitious effort from 35 yards but Joe Lewis in the Aberdeen goal watched it go wide of the target.

After 36 minutes the bottom club hit the woodwork when Ethan Robson watched his left-footed attempt strike the outside of Lewis' far post after Cosgrove had headed clear back in his own box.

There was some controversy four minutes before the interval. Connor MacLennan's cross appeared to be handled by Dundee skipper Paul McGowan, prompting a furious reaction from McInnes, but referee Andrew Dallas was up with play and dismissed their appeals.

On the stroke of half-time, McInnes was claiming again after the ball hit the hand of Dundee substitute Genseric Kusunga after home keeper Seny Dieng had spilled Niall McGinn's in-swinging cross.

The second half was just as hard-fought. Ryan McGowan was penalised for climbing on Cosgrove, and from the resultant free-kick McGinn hoisted his effort well over the bar.

But the visitors went ahead from the penalty spot after 59 minutes. McGinn's pace forced Callum Moore into a reckless challenge and referee Andrew Dallas quickly pointed to the spot.

Cosgrove stepped up to finish the job off and send Dieng the wrong way with a textbook effort.

Cosgrove then sealed matters in the 77th minute with a low finish after sterling work down the left by McLennan to send the large travelling support home happy to the Granite City.

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