[1] Heading toward the 2015–16 season, Mattisseck moved to the youth club of TuS Lichterfelde for a year, before signing with Alba Berlin.

[3] Initially intended to only be a supplementary player with SSV Lokomotive Bernau, Mattisseck impressed, and caught the attention of Alba Berlin head coach Aíto García Reneses.

[4] After eventually making his Bundesliga debut in March 2018, Mattisseck would later help the Alba Berlin U19 team win the junior championship.

[11] A year later, Mattisseck was named the MVP of the 2018 Albert Schweitzer World Under-18 Tournament, after he led Germany to the competition's gold medal.

[14] A few months later, Mattisseck was named to the Germany U20 national team, that won bronze at the 2019 FIBA U20 European Championship in July.