Inter Milan kept up the pressure on the top two in Serie A as the defending champion won at Venezia 2-0.
Hakan Çalhanoglu opened the scoring in the first half and Lautaro Martínez sealed the result with a stoppage-time penalty. Third-placed Inter moved to within two points of AC Milan and Napoli.
Napoli hosts Lazio on Sunday, when Milan welcomes Sassuolo.
Venezia remained six points above the relegation zone.
Inter was full of confidence ahead of the trip to Venice, having won five of its past six matches including a midweek victory over Shakhtar Donetsk to qualify for the Champions League knockout stages for the first time in 10 years.
Both teams struggled on Saturday to create chances in the early stages and Inter's best opportunity came in the 30th minute when Venezia goalkeeper Sergio Romero did well to parry an Ivan Perišic header.
Inter took the lead six minutes later as Çalhanoglu unleashed a powerful effort from outside the area that flew into the bottom left corner.
Venezia almost leveled shortly after with a screamer from Mattia Aramu that Inter goalkeeper Samir Handanovic kept out.
Inter had several opportunities to double its lead before eventually doing so in stoppage time. Venezia goalkeeper Ridgeciano Haps was penalized for handball and Martínez struck the resulting spot kick into the bottom left corner.
There was more misery for Juventus as it lost at home to Atalanta 1-0 and was roundly jeered by its fans.
That loss came four days after losing 4-0 at Chelsea in the Champions League.
Atalanta hadn't done much better, fumbling a lead twice in a 3-3 draw at Young Boys.
Duván Zapata scored the only goal in Turin, with a powerful effort in the 28th minute that went in off the underside of the crossbar.
Juventus almost leveled in the second half but Adrien Rabiot's effort was fingertipped wide by Juan Musso.
Juventus players Federico Chiesa and Weston McKennie went off injured during the match, to cap a miserable night for the Bianconeri.
Two late goals saw Empoli complete an extraordinary turnaround and beat Fiorentina 2-1.
Fiorentina seemed to be heading for the win after Dušan Vlahovic's 57th-minute opener but substitute Filippo Bandinelli leveled in the 87th and Andrea Pinamonti netted the winner two minutes later.
Also, Sampdoria came from behind to beat Hellas Verona 3-1.