Eintracht Frankfurt sporting director Bruno Hubner said the Bundesliga side are "still optimistic" about keeping star Ante Rebic.
The 25-year-old has been heavily linked to Serie A side Inter, while their neighbours AC Milan have also emerged as a possible destination for the Croatia international forward.
Eintracht – who reached the Europa League semi-finals last season – have already lost star duo Luka Jovic (Real Madrid) and Sebastien Haller (West Ham) during the transfer window.
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However, after Rebic's hat-trick in Eintracht's 5-3 win over Waldhof Mannheim in the first round of the DFB-Pokal, Hubner said: "We are still optimistic.