Serie A leaders Juventus maintained their eight-point cushion at the top of the division with a 2-0 win over Siena on Wednesday.
The Italian champions now have 46 points from 17 matches.
Inter Milan remained their closest challenger on 38 points after racking up a sixth consecutive Serie A victory by crushing Empoli 4-1.
AC Milan, one point further back in third, also enjoyed an impressive 3-0 win at Livorno. It was the Tuscan side's first home defeat of the season.
Fiorentina completed a clean sweep for the division's top four clubs with an edgy 1-0 win over Palermo to rise to 36 points.
Having looked unusually vulnerable during a 1-1 draw against Lazio on Saturday, Juventus's players were keen to stamp their authority on the championship.
Fabio Cannavaro gave them the ideal start, heading in from a corner in the 13th minute.
Juve continued to dominate possession, though Siena created a few chances of their own, the best of which came just before halftime when former Juve defender Igor Tudor narrowly failed to connect with a dangerous-looking cross in front of goal.
David Trezeguet wrapped up the win nine minutes after the restart when he ran on to a Mauro Camoranesi chip, rounded the keeper and finished into an empty net.
The goal was the French striker's 15th in as many appearances this season. He has scored in his last nine games.
Juve's win also guaranteed them the title of "winter champions", awarded to the team who lead Serie A at the midway point of the season, with two games in hand.
At the San Siro Inter Milan showed the same killer instincts that helped put four goals past Reggina at the weekend, going ahead after just four minutes when Empoli keeper parried an Esteban Cambiasso shot into the path of Adriano, who was left with an easy close-range finish.
HEAD CLASH
The Brazilian striker's contribution to Inter's win was cut short 10 minutes later, when he briefly lost consciousness following a clash of heads with defender Andrea Raggi.
His substitute, Julio Cruz, kept Inter on the right track, however, firing in their second goal from the edge of the area just before halftime.
Empoli midfielder Ighli Vannucchi pulled one back for the visitors, but goals by the in-form Luis Figo and Obafemi Martins re-established Inter's dominance.
While Inter versus Empoli promised to be a mismatch even before a ball had been kicked, AC Milan's visit to Livorno was tipped to provide an upset.
Milan had lost four of their eight away games prior to visiting Livorno and were playing a team whose excellent home record -- played eight, won six, lost none -- suggested that three points would be hard to come by.
Livorno started brightly and created the first good chance, Cristiano Lucarelli heading the ball over an open goal after a defensive mixup between keeper Dida and defender Dario Simic.
Milan were showing only flashes of their usual slick passing game, but in the 23rd minute Kaka and Andriy Shevchenko combined to slip the ball to Alberto Gilardino to go through alone on goal and beat keeper Marco Amelia.
Milan upped the pressure in the second half.
Fabio Galante cleared a Gilardino header off the line shortly after the break, but could not prevent the 23-year-old striker grabbing his second goal on the hour after a one-two by Shevchenko and Clarence Seedorf had cut through Livorno's defence.
Shevchenko got the goal he deserved in the 71st minute, heading home from Andrea Pirlo's free kick.
Fiorentina's win over Palermo, courtesy of Martin Jorgensen's first-half strike, was a much more edgy affair, but opened up a five-point lead on fifth-placed Livorno that could prove important when the scramble for Champions League places begins later in the season.
