AC Milan overtook Lazio for the Serie A lead with a 3-1 win over Palermo on Wednesday, but lost Alexandre Pato and Filippo Inzaghi to injury with the derby against Inter Milan coming up next.
It's the first time Milan has had the sole lead since November 2008.
Pato put Milan ahead in the 19th minute at the San Siro, Zlatan Ibrahimovic restored the lead with a penalty in the 77th and Robinho came off the bench to add the third goal in the 83rd.
Pato exited grasping his right thigh in the 65th and was replaced by Inzaghi, who appeared to twist his left knee in the 80th.
Lazio allowed a score from Marco Parolo in the 85th minute and lost 1-0 at Cesena, its second consecutive defeat after losing to AS Roma in Sunday's derby.
Milan has 23 points, Lazio is next with 22, Napoli has 21, while five-time defending champion Inter dropped to fourth with 20 after a 1-1 draw at Lecce, which equalized through Ruben Olivera after Diego Milito had put the injury-plagued European champion in front.
Inter and Milan meet Sunday.
Napoli won 1-0 at Cagliari with a last-second goal from Ezequiel Lavezzi, while Juventus drew 1-1 at Brescia, with Fabio Quagliarella and Alessandro Diamanti trading goals over a span of two minutes midway through the second half.
Juventus is fifth with 19 points and resurgent Roma moved into sixth a point back following a 3-2 win over Fiorentina. Fabio Simplicio, Marco Borriello and Simone Perrotta scored for Roma, while Alberto Gilardino and Gaetano D'Agostino found the net for Fiorentina.
Two days after hiring Davide Ballardini as its new coach, Genoa beat Bologna 1-0 with an 81st-minute goal from Omar Milanetto, and Maxi Lopez scored as Catania defeated Udinese 1-0. Also, Chievo Verona and Bari played a 0-0 draw.
