Inter Milan's seven-match winning streak in the Italian league was broken with a 1-0 loss at Lecce, which allowed Lazio to jump ahead of the Nerazzurri into fourth place.
Uruguayan midfielder Guillermo Giacomazzi scored in the 40th minute for Lecce and Inter had two goals called back for offside.
Inter was one win away from matching the club-record winning streak.
Massimo Oddo provided the pass for Giacomazzi, who used his chest to control the ball and slotted a low shot past goalkeeper Julio Cesar as defenders Lucio and Walter Samuel failed to intervene.
"We came up against a goalkeeper in great form, while we continually grew more nervous," Inter coach Claudio Ranieri said.
It was Lecce's first home win of the season and only its fourth overall.
Lazio won 3-0 at Chievo Verona with a first-half goal from Brazilian playmaker Hernanes and two strikes in the final minutes from veteran Germany striker Miroslav Klose.
Juventus, which edged Udinese 2-1 Saturday, leads Serie A with 44 points. AC Milan, which was hosting Cagliari later, is next with 40, followed by Udinese (38), Lazio (36) and Inter (35).
Elsewhere, Roma drew 1-1 at home with Bologna to stay sixth. Roma's 21-year-old midfielder Miralem Pjanic equalized with a splendid free kick in the 62nd minute after Bologna captain Marco Di Vaio had scored six minutes earlier.
Also, Genoa beat Napoli 3-2 with two goals from Rodrigo Palacio and one from newly signed Alberto Gilardino to get some revenge for a 6-1 loss to Napoli last month that cost Alberto Malesani his job.
In Sicily, Palermo beat last-place Novara 2-0, with Fabrizio Miccoli setting up two headers from Igor Budan; and Atalanta hung on with 10 men for a 1-0 win at Cesena following an own goal from Marco Rossi.
Fiorentina moved into the top half of the table with a 2-1 win over Siena in a Tuscan derby.
Stevan Jovetic put Fiorentina in front with a low shot four minutes in and Cesare Natali doubled the lead with a header in the 63rd before Emanuele Calaio pulled one back for Siena with a penalty in the 88th.
Making his debut after transferring from Juventus, Brazilian-born Italy forward Amauri had several chances for Fiorentina but couldn't find the target in his first action since the end of last season.