Aberdeen continued their recent resurgence under interim boss Barry Robson with an emphatic 3-0 Scottish Premiership victory over Hearts at Pittodrie.
The contest was all-but over by the interval, with the Dons three in front thanks to a double from the impressive Duk and a Mattie Pollock header.
There were no further goals in the second half but this was Aberdeen’s fourth win from their last five matches as they moved to within four points of their third-placed opponents.
Hearts just could not cope with the home team’s intensity, which was typified by Graeme Shinnie’s all-action, tenacious display.
Indeed, Shinnie played a big part in Aberdeen’s fifth-minute opener, nutmegging James Hill and sending in a low cross from the left.
Zander Clark could only parry the ball out as far as Duk, whose 12-yard volley nestled into the net aided by a slight deflection.
The hosts were rampant and it came as no surprise when they doubled their lead in the 21st minute.
A neat passage of play near the touchline culminated in Pollock delivering a precise cross and Duk found space in the box to glance a header into the far corner.
Pollock then went from provider to scorer in the 28th minute as Hearts’ afternoon showed no signs of abating.
Leighton Clarkson’s free-kick had whip and bend and Pollock, on loan from Watford, bulleted a header beyond the helpless Clark.
Yet it could, and probably should, have been four soon after, Ylber Ramadani firing wide from 12 yards after racing onto Duk’s pass.
The visitors were being pulled apart and, in a bid to stem the flow, boss Robbie Neilson hauled off Alex Cochrane for Stephen Kingsley although it could have been any player in a Jambos shirt given the hook.
Early in the second period, Duk tested Clark with a swerving strike from distance before Robert Snodgrass wasted a chance to pull one back for Hearts when through on goal and Lawrence Shankland passed up a decent opportunity.
With Jay Gorter ill, the fit-again Kelle Roos was back in goal for Aberdeen for the first time in two months but his opposite number Clark continued to be busier as he kept out another Duk effort.
The hosts eased off as time passed and saw the game out with minimal fuss to register a third straight home win and climb a place to fourth in the table.
Aberdeen return to Scottish Premiership action after the international break away to St Johnstone on April 1.
Hearts travel to Kilmarnock on the same day. Both matches kick-off at 3pm.