Real Madrid have been linked with him but the coronavirus pandemic has sparked much financial uncertainty as Manchester United are now looking to hijack the deal.
Speaking to Dutch outlet NOS, Ajax CEO Van der Sar said: “It’s clear that clubs like Real Madrid and United are showing interest in Donny van de Beek.”
Manchester United return to Premier League action on June 19 – two days after the season officially restarts.
The Red Devils will take on Tottenham in north London.
“We’ve been looking forward to these games for ages really,” said United boss Ole Gunnar Solskjaer ahead of the return. “It does make it feel like ‘yes, we’re here soon.’
“The first game is two weeks from today, so we need to step up the training and get an edge to our game again.
“Everyone knows that we will have to be at our best, and have to be focused against Tottenham. We know it’s a big game for everyone.
“We had Chelsea when we started the league this season so I’m confident that our players can go into the Tottenham game with that mentality of going there to play a very good game of football.”