Van der Sar is set to retire after the Champions League Final against Barcelona at Wembley next Saturday.
Fergie revealed: “Edwin has decided he wants to go out at the top, but he did have a wobble last week.
“He came to see me and told me he was thinking about changing his mind.
“I had to tell him to be quick because we are in the middle of concluding a deal for a new keeper. He came back a few days later to say he would be sticking with his original decision.”
