Eintracht Frankfurt sporting director Bruno Hubner said the Bundesliga side are "still optimistic" about keeping star Ante Rebic.
Rebic has been heavily linked to Serie A side Inter, while 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.
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."
41 - For the first time in almost 41 years, @eintracht_eng have won a cup match when two goals behind - the last time this happened was in September 1978 (3-2 at Werder Bremen). Fight. #SVWSGE #DFBPokal pic.twitter.com/CtahTrrjKR
— OptaFranz (@OptaFranz) August 11, 2019
Rebic was the hero away to the 3.Liga side on Sunday, scoring three goals in 12 minutes as Eintracht came from behind to win.
Mannheim led 2-0 after 11 minutes and 3-2 with 18 minutes remaining before Rebic's three-goal haul.
Asked about Rebic, Eintracht head coach Adi Hutter replied: "It's always an individual situation for each player.
"If someone has the opportunity to go to a top club, it will be difficult to keep him at the club."
Rebic has flourished since arriving from Fiorentina on an initial loan deal in 2016, scoring 17 Bundesliga goals and 25 in all competitions.
