Serie A's leading scorer Mateo Retegui netted as Atalanta beat Parma 3-1 on Saturday to go top of Serie A on goal difference, overtaking Inter Milan despite the reigning champions' rout of Verona.
Attacker Retegui claimed his 12 league goal of the campaign after just four minutes for the visitors before Ederson and Ademola Lookman scored to send them above Inter, who hammered Verona 5-0 earlier in the day.
Napoli drop down to the third before they host Roma on Sunday on Claudio Ranieri's return to top-flight management.
Atalanta coach Gian Piero Gasperini said his team were developing a winning mentality.
"We have to focus on winning every game we can and the rest is not really in our minds," he told Sky Sport Italia.
"That was the case in the Europa League too, we didn't start out thinking we'd win it, but as time wore on and we found ourselves in that position, we weren't going to hold back either."
Argentina-born Italy striker Retegui, 25, opened the scoring early on with a deft header before Atalanta were denied a second goal five minutes later.
Retegui's strike partner Lookman was adjudged to be offside by VAR following a Mario Pasalic pass.
Gian Piero Gasperini's Europa League champions finally celebrated their second after 39 minutes as Brazil midfielder Ederson scored his second goal of the campaign.
With 10 minutes of the second half played, the hosts cut the deficit as Matteo Cancellieri fired home.
Retegui was replaced by attacking midfielder Charles De Ketelaere as Gasperini eyed resting the attacker before Tuesday's Champions League trip to Young Boys.
Parma's hopes of denying Atalanta a seventh straight league win were dashed with a quarter of an hour to play as Lookman finally scored.
Nigeria's Lookman netted for a seventh time this campaign before La Dea held on to take top spot in the table.