Complex sentence: He made his debut in the Futsal-Bayernliga in Regensburg's 5-4 victory over SpVgg Bayreuth on matchday 3 and became one of the team's key players during his two-season stay at the club.
Split into simpler sentences: He made his debut in Regensburg's 5-4 victory over SpVgg Bayreuth on matchday 3. He became one of the team's key players during his two years' stay at the club.