Duk has caught the eye with his performances for Aberdeen in the Scottish top flight and the Pittodrie outfit could find it tough to hold on to him.
He is attracting serious attention from the English Championship, where Burnley, Blackburn and Hull are all keen.
Burnley have secured promotion to the Premier League and may be the more attractive option for Duk.
Blackburn meanwhile are battling to secure a playoff spot to give themselves a shot at promotion, while Hull are a lowly 15th in the Championship table.
Duk has so far found the back of the net 18 times for Aberdeen this season, with 16 strikes in the Scottish Premiership.
The Scottish side snapped up Duk from Portuguese giants Benfica, where he did not make a senior appearance.
It is unclear what valuation Aberdeen might place on Duk’s head if one of his suitors come calling in the approaching summer transfer window.
