Van der Sar worked with Onana at Ajax, where the young goalkeeper showed great promise and eventually earned a transfer to Inter Milan.
Van der Sar believes Onana's talent and mental strength will ultimately shine through, and he's urging Manchester United to give him time and confidence to succeed.
He recalls Onana's impressive performances at Ajax and notes that adapting to a new league and style of football can be challenging, but he's convinced Onana will become a top-notch Premier League goalkeeper.
