Napoli's forward from Poland Arkadiusz Milik trains separately because of an injury during a training session on the eve of the UEFA Champions League football match SL Benfica vs SSC Napoli on December 5, 2016 at the SSC Napoli training ground.  / AFP / CARLO HERMANN        (Photo credit should read CARLO HERMANN/AFP/Getty Images)
Donnerstag 16.06.2016, Europameisterschaft in Frankreich, Saint Denis, Deutschland - Polen, 0:0, Arkadiusz Milik (POL #7) , Toni Kroos (GER #18) (Photo by TF-Images/Getty Images)
Napoli's Polish forward Arkadiusz Milik celebrates after scoring during the Italian Serie A football match SSC Napoli vs Bologna FC on September 17, 2016 at the San Paolo stadium, in Naples. / AFP / CARLO HERMANN        (Photo credit should read CARLO HERMANN/AFP/Getty Images)
Napoli's forward from Poland Arkadiusz Milik (R) fights for the ball with Benfica's Swedish defender Victor Nilsson-Lindelof during the UEFA Champions League football match SSC Napoli vs SL Benfica on September 28, 2016 at the San Paolo stadium in Naples. / AFP / CARLO HERMANN        (Photo credit should read CARLO HERMANN/AFP/Getty Images)
Napoli's fans hold a banner in honor of Napoli's players from Poland Piotr Zielinski and Arkadiusz Milik before the start of the UEFA Champions League football match SSC Napoli vs SL Benfica on September 28, 2016 at the San Paolo stadium in Naples. / AFP / CARLO HERMANN        (Photo credit should read CARLO HERMANN/AFP/Getty Images)