Netherlands international Daley Blind has been diagnosed with inflammation of the heart muscle, Ajax have announced.
The former Manchester United defender suffered from dizziness in Ajax's Champions League defeat against Valencia on December 10.
Although Blind completed that game, he has not played since and was last week ruled out of his club's remaining matches in 2019.
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Ajax have now confirmed Blind will remain in Amsterdam to continue his recovery when the team travels to Qatar for a mid-season training camp.