It was reported in the Dutch media that the legendary former Netherlands striker has been suffering from heart palpitations following the death of his father last month.
AZ revealed that assistants Dennis Her and Alex Pastoor will take over the first team in the absence of Van Basten.
The club said in a statement on their website: "The absence of Marco van Basten will be longer than first expected. The coach has been struggling with physical discomfort for some time because of personal matters.
"These symptoms are so severe that it in the short term he is not able to competently carry out his work.
"Now Van Basten miss this Saturday's away match with FC Dordrecht."
Van Basten, 49, was confirmed as Dick Advocaat's successor at AFAS Stadion in April.
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