DORTMUND, Germany (AP) — Borussia Dortmund teenage star Konstantinos Karetsas was being treated at the hospital after slumping to the turf 25 minutes into his Champions League debut Tuesday.

“Konstantinos Karetsas had to leave the field due to circulatory problems,” Dortmund said in a statement. “Kosta is doing well under the circumstances and is on his way to the hospital for further tests.”

Facing Villarreal, the 18-year-old Greece prospect passed the ball to a teammate then signaled his distress to the referee before sitting on the grass.

Karetsas was treated laying down then taken away on a stretcher. The score was 0-0 at the time in what was a 3-2 win for Dortmund.

“I hope and I think that everything is OK and I hope that he’s back and fit with us soon,” Dortmund goalkeeper Gregor Kobel told broadcaster Amazon Prime.

Dortmund teenager Karetsas hospitalized with circulation issue after collapse in Champions League | iNFOnews.ca — Villarreal’s Pape Gueye, right, and Dortmund’s Konstantinos Karetsas challenge for the ball during the Champions League opening phase soccer match between Borussia Dortmund and Villarreal in Dortmund, Germany, Tuesday, Sept. 8, 2026. (AP Photo/Martin Meissner)

Karetsas and his Greece teammate Giannis Konstantelias were marquee signings for Dortmund in the offseason: Former Belgium youth international Karetsas for 30 million euros ($34.9 million) from Genk and Konstantelias for 26 million euros ($30.2 million) from PAOK.

The 23-year-old Konstantelias’ season was likely ended last month by an ACL injury on his Bundesliga debut.