Borussia Dortmund striker Sebastian Haller has been forced to leave the club's training camp in Switzerland after a testicular tumour was discovered.
The Ivory Coast international felt unwell on Monday morning, missing the 3-1 friendly defeat to Valencia later that day, and a series of medical tests took place. Further examinations are due over the next few days in a specialist facility.
"This news today came as a shock to Sebastien Haller and everyone else. The entire BVB family hopes that Sebastien makes a full recovery as soon as possible and that we can give him a hug again soon. We'll do everything in our power to ensure that he receives the best possible treatment," sporting director Sebastian Kehl said.
Dortmund's statement adds: "Borussia Dortmund request that the privacy of the player and his family is respected and that no inquiries are made. As soon as we have further information, we will consult with the player and inform you."
Haller signed for Dortmund earlier this summer, having impressed in the Eredivisie and Champions League with Ajax following a disappointing stint at West Ham.