And Feyenoord technical director Peter Bosz has admitted he is considering testing the resolve of Celtic, who landed the 29-year-old from PSV Eindhoven in 2006.
"There are a number of options in which we would like to investigate whether we could get him (Vennegoor of Hesselink)," Bosz told Dutch newspaper Algemeen Dagblad.
"Whether we could get him or not is difficult to say."