Inter's victory at the San Siro, sealed by Nicolas Burdisso's first-half header, stretched their lead at the top of the table to 14 points and extended their record run of consecutive Serie A victories to 16 games.

Roma's hopes of catching Inter were dealt a massive blow at Empoli where Nicola Pozzi's unstoppable fourth-minute strike secured three points for the plucky Tuscan club dreaming of a place in Europe.

In Saturday's other match, Ronaldo scored twice and set up a goal on his first start for AC Milan in their last-gasp 4-3 win at Siena, which moved them up to fifth place.

Inter, the reigning champions, remain way out in front with 63 points from their 23 matches played, followed by Roma on 49 and third-placed Palermo, who host Chievo on Sunday, on 42.

Empoli are fourth on 35 points, two ahead of AC Milan who were deducted eight points for their role in the Italian match-fixing scandal.

Inter seem set to retain the Scudetto, but Roberto Mancini refused to admit that the title was in the bag.

"The championship is definitely not over," the Inter coach, a former player with Sampdoria and Lazio, told Sky Sport Italia.

"It's going to be very difficult for Roma as we have a very good advantage over them, but I have had direct experience of comebacks in the final rounds of the championship in my career, one in favour and one against.

"We have to be careful and make sure we keep our foot on the accelerator."

Roma coach Luciano Spalletti said his team paid for their slow start at Empoli.

"We weren't in the fight at the start of the first half," he said.

AC Milan coach Carlo Ancelotti hailed the contribution of Ronaldo who joined the club from Spanish giants Real Madrid at the end of last month.

"Two goals and an assist is an excellent return in 90 minutes," Ancelotti said.

"To make such an impression here in such a short space of time has been a surprise for everybody."

Burdisso struck for Inter in the 11th minute.

Zlatan Ibrahimovic crossed from the right with the outside of his right boot and Argentine defender Burdisso planted a firm header past Marco Fortin.

Dejan Stankovic came closest to adding to Inter's lead when his fierce shot rattled the bar 16 minutes from time.

Only season-ticket holders were allowed into the San Siro under strict security measures brought in by the Italian government following the death of a policeman in Sicily earlier this month when Catania fans rioted.

Pozzi gave Empoli the perfect start against Roma, his thunderous effort giving Alex Doni no chance.

Roma were twice denied by the woodwork, with David Pizarro and Simone Perrotta both hitting the post.

Ronaldo put Milan ahead at Siena with a looping header before Simone Vergassola capitalised on a defensive mix-up to equalise.

Milan restored their lead when Ronaldo set up Oliveira only for Massimo Maccarone, a January signing from English Premiership side Middlesbrough, to level with an agled shot.

After Milan had Christian Brocchi sent off, Ronaldo grabbed his second goal. tapping home Kaka's cross in the 81st minute.

Maccarone made it 3-3 with an emphatic finish after more poor defending from Milan before Molinaro put through his own net.