Dutch veteran van der Sar turned 40 earlier this year, and is widely regarded as one of the best goalkeepers in United's history - certainly the outstanding successor in a long line of stoppers to follow Danish star Schmeichel.
"Both of them are magnificent," Sir Alex told his pre-Sunderland press conference. "I’m very lucky to have had them both. It’s marvellous.
"To be playing at our level at 40 years of age is amazing. You can only do it if you’ve got the structure of mind that Edwin’s got to be able to programme himself and train the way he does. He’s phenomenal, he truly is. He’s an outstanding man. I should have signed van der Sar after Schmeichel. I made a mistake. But now we think we know where we’re going."
New signing Anders Lindegaard has already been snared as United look to the future. The Danish international has trained at Carrington for much of December, which Sir Alex sees as an important part of his integration.
"It’s a Bank Holiday on the third of January, which means we can’t register him until after the Stoke City game," said the manager. "But he is training with us and that’s important. It’ll bring him to a fair level of fitness because he hasn’t played for a few weeks, so we’ll see how his progress goes."