Ajax have announced that their captain, Siem de Jong, has been diagnosed with a collapsed lung.
De Jong, 24, is set to miss around six weeks of the new Eredivisie season as a result.
A statement on the Ajax official website read: “Siem de Jong was found to have a collapsed lung on Monday. The Ajax captain will spend the next few days at least in hospital.”
His lung will now be drained, and the club statement added: “It has not been determined how and when the Ajax player sustained this injury. The total recovery will take at least six weeks.”
The player wrote on his official Twitter account: “Collapsed lung?!?!? Now a few days in hospital and then a few weeks' rest...”
He thanked fans for their positive messages and added: "Hope to be fit again soon."