Dortmund reportedly make €20m offer for talented Mainz defender

The 18-year-old defender made 15 Bundesliga appearances in 2025-26, producing a goal and an assist.

Photo: Christof Koepsel/Getty Images.

Rumours from Poland indicate that Borussia Dortmund has already submitted a concrete offer to Mainz for Kacper Potulski.

According to a report by 'Przeglad Sportowy Onet', the Westphalian giants have produced a bid of €20million for the centre-half.

Mainz has reportedly rejected this offer and is demanding a higher sum for the defensive talent who has just been called up by Poland.

Potulski – who is contracted with Mainz until 2028 – joined the club from Legia Warsaw's youth academy in the summer of 2023.

While his deal reportedly does not include a release clause, Bayer Leverkusen are also among the clubs said to be keen on him.

BVB has already secured a defensive deal worth around €20million with the signing of 19-year-old Joane Gadou from RB Salzburg.