Watzke also took the opportunity to reveal an elite European club made an approach for the winger, but the unnamed club was told the 19-year-old was not for sale.
Sancho shot to prominence last season with his brilliant form for the Bundesliga side, scoring 13 times and making 19 assists in all competitions.
Manchester United were linked with the England international following his impressive performances for club and country.
However, the Premier League club were reportedly told in no uncertain terms that he was not for sale.
In an interview with Ruhr Nachrichten (via the Manchester Evening News), Watke said: “A chief of one of the super clubs asked me back in spring if there was a chance [to sign Sancho] but I told him straight away he should forget about it and he never contacted me again.
“He knew I meant what I said.”
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