Inter Milan's hopes of a fifth successive Serie A title suffered a setback on Saturday night as Jose Mourinho's side was held 1-1 at Palermo.
The Nerazzurri, perhaps fatigued by their Champions League heroics at Chelsea in midweek, could now be overtaken by city rivals AC Milan on Sunday when the Rossoneri take on Napoli at the San Siro.
Diego Milito fired Inter ahead from the penalty spot after 10 minutes but Edinson Cavani levelled after 24 minutes and neither side could find a winner.
The result left Inter two points clear of Milan, having played a game more.
Third-placed Roma is four points adrift of Inter after Mirko Vucinic netted a hat-trick in a 4-2 win over Udinese.
Luca Toni fired the Giallorossi in front after 14 minutes and Vucinic doubled the lead with his first after 24 minutes.
However, Palermo hit back to go in front with two goals from Antonio Di Natale, one of which came from the penalty spot.
But Vucinic restored the hosts' lead from the spot after 66 minutes and netted his third and Roma's fourth seven minutes from time.
Eighth-placed Fiorentina defeated seventh-placed Genoa 3-0, with goals from Mario Alberto Santana, a 73rd-minute penalty from Alberto Gilardino and El Khouma Babacar's 86th-minute effort.
Fiorentina 3 (Santana 4, Gilardino 73p, Babacar 86)
Genoa 0
Palermo 1 (Cavani 24)
Inter Milan 1 (Milito 10p)
Roma 4 (Toni 15, Vucinic 24, 66p, 83)
Udinese 2 (Di Natale 38p, 61)