Borussia Dortmund started their Champions League campaign with a turbulent 3-2 win over Villarreal at the Signal Iduna Park, but the result has been overshadowed by serious concern over 18-year-old Konstantinos Karetsas. The Greek winger collapsed without contact after 23 minutes, was carried off in tears, and two days later remains in hospital with no confirmed diagnosis. Sportdirektor Ole Book said further tests are ongoing and the club wants to get to the bottom of the incident, though he offered cautious reassurance that it does not appear comparable to Christian Eriksen's cardiac arrest at Euro 2021. Karetsas will miss the next Bundesliga fixture against Paderborn on Saturday.

The injury situation is a genuine concern. Karetsas joins a list that already includes Nico Schlotterbeck, Emre Can, Filippo Mane, and Ramy Bensebaini, while fellow new signing Giannis Konstantelias ruptured his cruciate ligament on the opening Bundesliga weekend and underwent successful surgery this week. Arsenal loanee Ethan Nwaneri came on as replacement against Villarreal and will be needed.

On the pitch, there were real positives. Joey Veerman was outstanding in midfield, registering 99 touches and completing 82 of 87 passes, and Serhou Guirassy proved the match-winner. Despite the chaos, Dortmund sit third in the Bundesliga with six points from two games, and the Champions League victory provides a platform to build on after last season's playoff exit to Atalanta.