The 26-year-old midfielder returned to the Bundesliga in January after a difficult stint in Italy with Juventus.
Since completing his move to Dortmund, Can has quickly realized that the English international has world class capabilities.
He told Bild via the metro: “I knew he was a very good player before I even joined Dortmund.
“But since my arrival, I have discovered that he is world class and perhaps the best player of his age.
“He has everything a top footballer needs and has a great future ahead of him. “
A previous Bild report had suggested that Liverpool were looking to tempt Sancho to join the club with what the German publication described as “mega-wages”.
Must read Liverpool FC news
The 20-year-old, who has scored 14 goals and completed 16 assists in 23 high-flying outings, has also been linked to Chelsea and Manchester United.