The 21-year-old Denmark international was reported to be in London on Thursday ahead of a move to White Hart Lane.
Eriksen has been linked with moves away from the Amsterdam Arena over the past few seasons after impressing for the Eredivisie side.
Van der Sar - who is now marketing director at Ajax - admitted it would be a big blow to lose Eriksen, but knows he has the quality to succeed in England.
"He's a very good player and I would be sorry if he were to leave us,” he said. “He has great quality.
"(He) is two-footed, is very quick, gives you a lot of pace on the ball and his corners and free-kicks are very good.
"So I'm sure if he went to Tottenham he would be a great player there.”
Eriksen signed for Ajax in 2008 as a youth player and broke into the first team in 2010.
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