Borussia Dortmund have had a €20million offer for Mainz centre-back Kacper Potulski rejected, according to reports in Poland. The offer, made for the 18-year-old defender, was turned down as Mainz are holding out for a higher fee for the Polish youth international.
Potulski joined Mainz from Legia Warsaw’s youth academy in the summer of 2023 and has quickly established himself as a promising talent in the Bundesliga. He made 15 appearances in the 2025-26 season, contributing with one goal and one assist. His recent form has also earned him a call-up to the Poland national team, further increasing his profile.
Przegląd Sportowy Onet first reported Dortmund’s interest and the subsequent bid. While Potulski is currently contracted to Mainz until 2028, the club are reportedly aware of significant interest from other Bundesliga sides. Bayer Leverkusen are also understood to be monitoring the situation, potentially creating a bidding war for the young defender.
Dortmund have already been active in strengthening their defence this transfer window, recently completing a deal worth around €20million for 19-year-old Joane Gadou from RB Salzburg. The pursuit of Potulski suggests that the club are prioritising reinforcing their backline ahead of the upcoming season, despite already adding Gadou. The rejection of their initial bid indicates that Dortmund may need to significantly increase their offer to secure Potulski’s signature.
Securing a young, promising defender like Potulski would provide long-term stability for Dortmund’s defence and potentially increase competition for places in the squad.
