Foster has endured a turbulent few weeks, being blamed for two Manchester City goals in the thrilling Old Trafford derby last month before being brushed aside far too easily by Sunderland's Kenwyne Jones last weekend.
A chest problem then prevented him joining England on international duty this week, and with speculation mounting that Sir Alex Ferguson will launch a £10 million raid on CSKA Moscow for Igor Akinfeev if Van der Sar calls it a day at the end of the season, Foster's Red Devils career appears to be under threat. However, Van der Sar can offer some words of comfort.
Although the 38-year-old has enjoyed a stellar career, featuring a Champions League win as a youngster with Ajax before his second such success with Manchester United in 2008, the Dutchman had to learn the hard way too. And he is confident Foster will emerge a stronger figure and a better goalkeeper for what he is going through at present.
"Nobody has a clear path in their career," Van der Sar told the Manchester Evening News. "You go up and down. You just have to make sure that the downs are not as deep as the ones you go up. I had similar things when I was young. That is what makes you the man and the player you become as a goalkeeper.
"Ben certainly has the strength of character to overcome what he has been through. How he deals with it will shape the player he will be. He is a very strong guy. I have sympathy for him but I have no worries about him."
After a successful reserve team comeback against Everton on Tuesday, Van der Sar is in line for a recall when United entertain Bolton next Saturday in a match that must be won just eight days before the blockbuster showdown with Liverpool at Anfield.
Sitting on the sidelines since breaking two fingers during a pre-season encounter with Bayern Munich has been a frustrating experience for a player who will celebrate his 39th birthday later this month.
Van der Sar knows the end of his career is approaching, even though he will not make a decision about his short-term future until later this year, and he does not want to miss any more action.
"I want my place back," he said. "Playing in the reserves on Tuesday was an ideal moment for me to get a game under my belt before the Premier League begins again after the international break. I needed a game."