As Chelsea prepare for the first leg of their Champions League clash with Napoli at San Paolo on Tuesday evening, it’s tempting to recall how André Villas-Boas spent a season in Serie A scouting opponents for Inter Milan as an assistant to José Mourinho.   Italian football is far from unfamiliar territory to the Chelsea manager. He knows its teams, coaches and players, and won’t be under any illusion as to the threat Napoli pose.  “We have one of the most difficult draws,” Villas-Boas said in December.   Napoli’s rise has been one of the major talking points of this season’s Champions League. Re-founded following bankruptcy in 2004, it’s nothing short of remarkable that in the space of seven and a half years, they…