The 17-year-old forward joins the Bundesliga side for a reported €2.5million, according to Bild.
Ben Khalifa impressed during the Under-17 World Cup last year and has also been linked with Arsenal, Inter and Ajax.
The 17-year-old forward joins the Bundesliga side for a reported €2.5million, according to Bild.
Ben Khalifa impressed during the Under-17 World Cup last year and has also been linked with Arsenal, Inter and Ajax.
