Ajax's coach Ronald Koeman will have to miss the services of midfielder Tomás Galásek on Sunday. The Czech sustained an injury in Tuesday's UEFA Champions League match against AC Milan.
Galasek hurt his medial knee ligament in that match.
Ajax play against NAC on Sunday April 13 for the Holland Casino Eredivisie, the Dutch league.
It is uncertain whether Galasek will be able to play in Wednesday's Cup semi-final against Feyenoord.