Napoli was unfortunate when Dries Mertens hit both posts at the Stadio San Paolo and Cagliari substitute Lucas Castro was left completely unmarked in the center of the area to head in the winner in the 87th.
Inter restored its two-point advantage over Juventus, which beat Brescia 2-1 a day earlier. Atalanta moved up to third with a 2-0 win at Roma, while Napoli dropped to fourth — level on points with fifth-placed Cagliari.
ATALANTA 3RD AGAIN Atalanta showed off its intentions of maintaining its Champions League status by beating a Roma team that had won three straight in all competitions. Substitute Duvan Zapata scored in the 71st and Marten De Roon sealed it in the 90th at the Stadio Olimpico.
Atalanta finished a best-ever third in Serie A last season but was humbled in its Champions League debut this month, losing 4-0 at Dinamo Zagreb. However, the Bergamo-based squad bounced back with two late goals for a 2-2 draw with Fiorentina on Sunday and has now handed Roma its first loss.
Roma, which has struggled defensively at times under new coach Paulo Fonseca, is sixth. Defender Chris Smalling, on loan from Manchester United, had a strong debut for Roma in the first half. OTHER RESULTS
German Pezzella and Federico Chiesa scored as Fiorentina earned its first win of the season, 2-1 over 10-man Sampdoria. Gervinho had two goals disallowed by the VAR and Roberto Inglese failed to convert a penalty kick but Parma still beat Sassuolo 1-0 with an own goal from Mehdi Bourabia five minutes into stoppage time.
Marco Mancosu converted two penalties as Lecce won 3-1 at Spal; while Bologna's Nicola Sansone missed a penalty off the crossbar in a 0-0 draw at Genoa.
More AP soccer: https://apnews.com/apf-Soccer and https://twitter.com/AP_Sports
Andrew Dampf on Twitter: www.twitter.com/AndrewDampf