Kacper Potulski

Kacper Potulski is a Polish defender whose path into senior football ran through Mainz's youth teams. He moved from Legia Warsaw to Mainz in 2023, then progressed from the under-19s toward the under-23s. Mainz's technical director described central defence as his development route, citing his height and willingness to learn.

His professional debut came in a European competition. On 2 October 2025, Potulski started away to Omonoia in the Conference League as Mainz won 1-0. A preseason camp place earlier that summer had only put him among the travelling group; the Nicosia starting place was the confirmed match appearance. It exposed him to a back line facing aggressive pressing and quick transitions.

Potulski's defensive work is about more than his size. In Mainz's December 2025 interview, the club singled out his tackling, positioning and contribution to building play. Those are linked jobs for a central defender: hold a useful position, decide when to engage, then move possession out after a regain. Poland's federation described him as right-footed but used on the left of a back three. This describes role demands, not mastery of each part.

A second Bundesliga appearance produced a memorable attacking moment. Against Bayern Munich on 14 December 2025, he met a free kick at the far post and headed in Mainz's equaliser in a 2-2 draw. The goal illustrated how a tall defender can matter at attacking set pieces as well as in his own penalty area. Potulski also acknowledged that his challenge on Harry Kane led to a late penalty and spoke about learning to judge such contact more carefully.

The move from academy football to the first team was gradual, and Mainz later called 2025/26 his breakthrough. Club officials said his work in first-team training had impressed two coaches. Youth promotion, preseason selection and a professional debut were separate steps; none alone established a regular senior role.

Potulski's international story distinguishes youth status from senior participation. Mainz called him a Poland youth international in July 2025. On 31 May 2026, Poland's federation recorded his senior debut in a friendly against Ukraine: he replaced Jakub Kiwior during the second half. He then scored against Nigeria in a June friendly and started in a three-man defence against Bosnia and Herzegovina that September. Those are appearances, not merely squad selections.