Mainz reject Borussia Dortmund's €20m bid for 18-year-old Kacper Potulski

Borussia Dortmund made a €20 million bid for Mainz defender Kacper Potulski, 18, who has recently made his Bundesliga debut and earned his first Poland senior cap. Mainz rejected the offer immediately. Potulski has attracted widespread transfer market interest after a rapid rise through senior football over the past few months.