De Jong out for six weeks
Ajax skipper Siem de Jong will be sidelined for six weeks after he was diagnosed with a collapsed lung.
The Dutch international sought medical attention on Monday after suffering persistent coughing and chest tightness.
It is not known how long the star midfielder has had the problem or how it happened.
He featured in the club's first two Eredivisie fixtures - scoring in Sunday's 3-2 loss to AZ Alkmaar - but will miss several club matches as well as two World Cup qualifiers in early September during his enforced layoff.
If de Jong returns on schedule in six weeks he will be available for the September 22 clash against PSV Eindhoven.
The 24-year-old is upbeat about his prospects of a speedy return.
"I hope that I will get fit quickly," he Tweeted from hospital on Monday.
Meanwhile, defender Ricardo van Rhijn will also miss this weekend's match with Feyenoord after accepting a one-match ban following his red card in Sunday's match.