Former Manchester United, Juve and Ajax stopper Van der Sar spoke to ESPN FC's Shaka Hislop (h/t Ollie Lewis of MailOnline) about De Ligt's early struggles in Turin and how he compares to team-mate Ronaldo:
"He had been all his life at Ajax. So to step away, move with your girlfriend and the family to a different city, a different language. But his mentality and the way he wants to improve, he wants to be the best defender in the world. And I've seen that with a few players. One of them is playing in the same team, Cristiano Ronaldo.
"When I played at Man United with him, he had the same desire and attitude to work hard, to become better every training. And that's the same mentality and hunger as Matthijs de Ligt."
Those words are quite the ringing endorsement for a young player who has so far found it tough to make the grade in a Juve shirt. De Ligt joined the Bianconeri during the summer in a deal worth £67.5 million after starring as captain for Ajax.
Things haven't gone smoothly, though, with De Ligt increasingly prone to mistakes. His presence at the heart of the back line has turned a usually stout Juve defence into a surprisingly leaky unit:
De Ligt's problems at club level have even extended to the international stage. He was victimised early on when the Netherlands beat Northern Ireland 3-1 in a qualifier for UEFA Euro 2020 on Thursday:
Van der Sar is right to emphasise the impact of the dramatic changes in De Ligt's life since he left Amsterdam. While a lot has been expected of him in Turin, he has possibly been thrust into a key role sooner than anticipated thanks to the knee injury suffered by Giorgio Chiellini.
Living up to the moniker of best in the world at his position won't come until De Ligt proves he can cut it at a higher level. Showing he can will require refining his game to take fewer chances than he did at Ajax.
De Ligt played an aggressive style for the Eredivisie giants, often leading a high line. Juve tend to operate in a more cautious manner, although Maurizio Sarri hasn't been afraid to have his defenders apply more pressure on the opposition.
Part of helping get De Ligt up to speed involves a burgeoning partnership with Leonardo Bonucci. The 32-year-old is a calm figure of authority who is technically adept enough to play out from the back.
Bonucci can help De Ligt cultivate some much-needed assurance and patience. The youngster has the natural ability to follow a similar path as Ronaldo, who went from a raw talent to perhaps the best player of his generation.