Preparation for exams often comes at the expense of free time, but for Bayer Leverkusen midfielder Kai Havertz it will cost him a Champions League appearance.
Teenager Havertz became the youngest player to appear in the Bundesliga for Leverkusen when he made his debut in a 2-1 defeat against Werder Bremen last October.
The 17-year-old got his first outing in the Champions League in the 4-2 defeat to Atletico Madrid in the first leg of their last-16 tie last month, but it could prove to be his last of the season with schoolwork taking priority.
Instead of travelling to Spain for the return match at the Vicente Calderon on Wednesday, Havertz will be hoping Leverkusen make the grade without him as he remains in Germany for what the club branded "important exams".
The German side will also be without injured quartet Omer Toprak, Jonathan Tah, Stefan Kiessling and Lars Bender, while Benjamin Henrichs is suspended.