Red-hot Fiorentina replaced Inter Milan as Serie A leaders by cruising to a 3-0 home victory over Atalanta on Sunday.
Lorenzo Insigne struck twice and set up another as Napoli romped to a 4-0 win over AC Milan at the San Siro.
Napoli made it three wins out of three for Italian sides in the Europa League on Thursday night with a 2-0 victory at Legia Warsaw.
Juventus' poor Serie A start continued with defeat at Napoli, while Roma returned to winning ways against struggling Carpi.
Juventus could only draw 1-1 at home to Frosinone in Serie A on Wednesday, as leaders Inter Milan beat Hellas Verona 1-0.
A Gonzalo Higuain-inspired Napoli ran riot against Lazio while there were also wins for Inter Milan and Fiorentina.