Napoli slumped to their second straight Serie A loss as Udinese snatched three points at the Stadio Friuli.
Reigning champions Sevilla, Inter Milan, PSV and Napoli were amongst the winners in the Europa League group stage.
Napoli boss Rafael Benitez says he is set to enter talks over a new contract, despite being linked with Newcastle.
Napoli coach Rafael Benitez struggled to find an explanation for his team's 1-0 home defeat to Chievo.
AC Milan edged a nine-goal thriller with Parma at the Stadio Tardini to join Juventus and Roma at the top of Serie A.
Maxi Lopez scored the only goal of the game as Chievo upset Napoli 1-0 at the Stadio San Paolo.
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