Complex sentence: After three years at the club's reserve, Boenisch made his professional debut for Schalke 04 on 11 February 2006, coming on as a substitute in the 86th minute, in a 7--4 home win against Bayer 04 Leverkusen.
Split into simpler sentences: After three years at the club's reserve, Boenisch made his professional debut for Schalke 04 on 11 February 2006. He was substituted on in the 86th minute, in a 7--4 home win against Bayer 04 Leverkusen.