The 18-year-old Shapovalov, who claimed the juniors' title at Wimbledon in 2016, defeated eighth seed Jo-Wilfried Tsonga of France in straight sets in the second round of the U.S. Open on Wednesday.
"He is a serious talent. To be 100 percent honest, you cannot compare Shapovalov to any other youngster," said Wilander, at the U.S. Open as an analyst for Eurosport.
"He is a completely different level. It's like watching a combination of Nadal and Federer at 18 years old. He has the fire of Nadal and the speed around the court of Nadal and he has the grace of Federer - it's unbelievable.
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"He really captivates the crowd. Last night it was like ‘Oh my god, where does this kid come from?’ He flies. I’m really really impressed. The best players in the world better watch out for him now.”
Shapovalov, who next faces Britain's Kyle Edmund, reached the semi-finals at the Rogers Cup in Montreal earlier this month after beating Nadal in the third round.
(Reporting by Julien Pretot; Editing by Frank Pingue)
