According to Sky Sports Germany reporter Florian Plettenberg, the Hoops had been interested in signing the 24-year-old before the close of the transfer window, although the promising German is said to have rejected the move.
Writing on Twitter about that interest, the transfer insider revealed: “News #Hack: @CelticFC was also interested but he won’t join them and he said NO to a transfer. Basel is hot instead.”
The former Nurnberg marksman – who only made the move to his current club last summer – is believed to be now closing in on a move to FC Basel, with the Swiss outfit set to strike a seven-figure agreement of around €1.5m (£1.2m) for his signature.
That news will seemingly come as a blow for title-winning coach Ange Postecoglou, with the 57-year-old likely to have been keen on adding further depth to his attacking ranks even after the recent addition of Sead Haksabanovic from Rubin Kazan.
The former Yokohama F. Marinos boss has proven himself an astute operator in the transfer market in recent times, with Hack likely to have been another bargain gem who could well have thrived for the Old Firm giants.
The £1.8m-rated winger has scored three goals and provided seven assists in just 38 games in all competitions thus far for his current club, having caught the eye last term despite Bielefeld’s eventual relegation from the Bundesliga.
The 5 foot 9 menace has started the new campaign in fine fashion, having scored two goals in the opening six league games in the German second tier, proving himself a real attacking threat from his left-wing berth.
With both Mikey Johnston and Albian Ajeti appearing set for the exit this summer after falling out of favour under Postecoglou, the Celtic boss could well be in need of new additions to help fill the void, particularly with squad depth set to be vital amid their domestic and European commitments.
Securing the services of the former Germany under-21 international would have offered quality cover and competition in the forward ranks and for a seemingly cut-price fee, with few talents of that ilk likely to become available so cheaply.
Therefore, the 57-year-old – whose birthday is today – is likely to have the celebrations tampered by Hack’s rejection of Celtic’s apparent interest.