Complex sentence: He made his debut on 2 February in Bayer Leverkusen's 0--1 loss to Kaiserslautern in the DFB-Pokal, playing as a left-back.
Split into simpler sentences: He made his debut on 2 February in a 0--1 loss to 1. FC Kaiserslautern for the DFB-Pokal, playing as a left-back.