The Ajax manager believes the Danish midfielder's proposed departure from the Amsterdam ArenA to join Spurs represents a huge blow for the Eredivisie outfit
The club's technical director Marc Overmars revealed that Spurs have opened talks with the Eredivisie club over the signing of the Denmark international.
De Boer praised the players's professional attitute during his time at the Amsterdam ArenA and says the club would reluctantly have to sell him.
"We always came along together very well. Footballers who are good player and also ideally professionals, are ideally players for a coach," the Ajax boss told De Telegraaf.
"His departure is a huge blow for us, because Chris is terribly important for us.
De Boer doesn't know if Ajax will reconsider their goals for this season now Eriksen is close to leaving. He says it depends on the replacement he is able to recruit.
"It depends on which player we can buy or take over on loan. Not from the level from Eriksen, but close to it."