The Netherlands international custodian broke his right thumb during practice on Saturday and was initially slated to be out for between four and six weeks.
But the Dutch giants have now said that the 28-year-old will remain on the sidelines for between seven and nine weeks as they used a different operation technique to enable him to recover fully from his injury.
Back-up goalkeeper Kenneth Vermeer has recovered from an Achilles tendon problem and has resumed training, but he will not be able to play any game for Ajax for the next few weeks, meaning that third choice Jeroen Verhoeven will get the chance to prove his worth in the upcoming weeks.
Ajax are currently third in the Eredivisie and are three points off the pace. On Thursday the former European champions travel to Russia to take on Spartak Moscow in the second leg of their round of 16 tie in the Europa League, having lost the first leg 1-0 in Amsterdam last week.
This Sunday, the Godenzonen have an early kick off when they are up against ADO Den Haag which promises to be another stern test for Verhoeven. You can watch the game live on www.LiveDutchEredivisie.tv.