Celtic have made an opening offer for him and he expects more to happen in the coming days. Weissman has been in incredible form since moving the Austrian Bundesliga club, netting 37 goals in 40 games.
The Hoops are looking for another striker to compete with Odsonne Edouard and Leigh Griffiths and Weissman fits the bill to what they are looking for.
But Riegler believes that the new few days could decide Weissman's future with the German Bundesliga now over, and clubs planning for next season.
He told Kleine Zeitung: "As you already know, he wants to go to Germany or England. Here, however, we still have no inquiries.
Read more on dailyrecord.co.uk