Inter Milan maintained their seven-point lead at the top of Serie A after Zlatan Ibrahimovic's double helped the champions to a 3-2 win at Siena yesterday.
AS Roma moved back up to second but had to come from behind to beat Atalanta 2-1 thanks to Francesco Totti's low free-kick and Mancini's thumping strike.
Returning from a three-week mid-season break, unbeaten Inter would not have expected such a tough match at lowly Siena, where they clinched the title last season.
Ibrahimovic converted a debateable penalty on 26 minutes when Julio Cruz collided with Paul Codrea.
Siena equalised quickly when Inter defender Ivan Cordoba appeared to get the last touch under pressure from Massimo Maccarone but the champions went back in front on the stroke of half-time when Esteban Cambiasso slid in Ibrahimovic's pass.
The Swede grabbed his 11th of the league campaign in the second half with a cracking shot and, despite Fernando Forestieri's late goal, Inter hung on for their seventh straight Serie A win and 11th successive victory in all competitions.
Roma went above Juventus, who drew 1-1 at Catania on Saturday and are now three points behind in third, while Udinese stayed fourth after Fabio Quagliarella secured a 1-0 win at bottom side Cagliari.
Fiorentina are a point further back in fifth after Adrian Mutu's brace set up a 2-1 win at Parma.
Antonio Cassano scored one and was again influential in Sampdoria's 3-0 home win over Palermo, their main rivals for a Uefa Cup spot. Lazio's poor season continued when they were unlucky to lose 2-1 at home to Genoa.
AC Milan came from 2-1 down to defeat Napoli 5-2 at the San Siro last night. Ronaldo opened the scoring before Roberto Sosa and Mauriizio Domizzi put the Naples side in front.
Clarence Seedorf equalised for the European champions before Ronaldo, Kaka and Alexandre Pato scored to give Milan the victory.