Leaders Internazionale maintained their unbeaten record and restored their advantage to eight points at the top of Serie A.
Inter's latest success came at Catania with a 2-0 success. Two goals in three minutes from Esteban Cambiasso (64) and David Suazo (67) sealed victory for Roberto Mancini's side.
Juventus kept up their pursuit of the top two with a 2-1 victory over high-flying Udinese, while Milan made it four wins in a row.
Milan started the day 20 points behind city rivals and Serie A leaders Internazionale, and they were made to work hard before seeing off Siena 1-0.
Teenager Alberto Paloschi scored the crucial goal, on his league debut, on 64 minutes, before Simone Vergassola was sent off for Siena eight minutes from time.
Juventus have been in fine form in recent weeks and they came from behind to defeat Udinese 2-1 and move to within four points of Roma in second.
Andrea Dossena put Udinese ahead after six minutes but Mauro Camoranesi drew Juve level on the hour mark and Vincenzo Iaquinta popped up with the winner in the 76th minute.
Sampdoria moved up to seventh with a hard-fought 2-0 win against Napoli.
It took until the 76th minute for Gennaro Delvecchio to break the deadlock, and Daniele Franceschini added a second after 82 minutes.
Palermo slipped to a 3-1 defeat against Torino despite taking the lead through Amauri after 36 minutes.
Almo Diana equalised in the 59th minute and David Di Michele fired Torino 2-1 ahead on 70 minutes.
Amauri was sent off five minutes later and Torino made the most of their extra man to seal the points with a second goal from Di Michele on 81 minutes.
Empoli boosted their chances of escaping relegation as they piled more pressure on out-of-form Lazio.
Ighli Vanucchi scored the only goal of the game after seven minutes for Torino, while Aleksander Kolarov was sent off for Lazio with three minutes of the match remaining.
Bottom club Cagliari were denied a crucial win as struggling Parma hit back from going a goal down to draw 1-1.
Genoa rescued a point at Livorno as Marco Di Vaio's strike eight minutes from time cancelled out Francesco Tavano's opener (15).