Roma halted AC Milan's charge towards the Scudetto by inflicting the first defeat on the Rossoneri in eight matches with a narrow 1-0 win at the San Siro.
A goal from former Milan striker Marco Borriello in the 69th minute earned the Giallorossi all three points and took them back into the race for the Serie A title, seven points behind their opponents. Milan had the most of the possession and the better chances, but lacked the cutting edge that had taken them six points clear at the top in recent weeks.
Victory was vital for Claudio Ranieri's team, who would have fallen 13 points off the leaders had they lost. Instead they are now just seven points behind Milan whose lead will be cut to three points should either Juventus, Napoli or Lazio win on Sunday.
French winger Jeremy Menez, who created the winning goal, believes the win was a crucial one.
"It was important to win most of all to show that we're still in it, that we're Roma," he said.
"Before heading off on holiday we've won an important game. We believe in the title and we always have.
"The season is long and we hope we'll continue to do well after the winter break," added the Frenchman.
Milan coach Massimiliano Allegri, meanwhile, complained that his team had not been clinical enough. "As we didn't play particularly well we deserved a draw but when you're not nasty enough in the right moments, these things can happen."
Milan started the way they had finished the last two games, which they won by the same 3-0 scoreline, with Robinho coming close to scoring for the third consecutive match in the fifth minute, but he shot wide of the far post after taking advantage of a slip by Philippe Mexes.
The home side dominated the first ten minutes and created several openings, but never tested Doni in the Roma goal. Roma's first chance came after half an hour when the lively Jeremy Menez pounced on a loose ball from Ignazio Abate, but shot over from 18 yards.
Milan still should have gone ahead in the 35th minute when Zlatan Ibrahimovic beat the offside trap, but he got the ball caught up a bit in his feet and his attempted lob over Doni was instead easy for the Roma goalkeeper to save.
Roma grew in confidence with every passing minute and with every chance Milan wasted.
In the second half, they were more than a match for their hosts and the first big chance came Borriello's way on the hour mark, but he slipped just before shooting and Alessandro Nesta covered and blocked.
The former Milan striker got the decisive goal in the 69th minute, although he knew very little about it. Menez's cross from the right was struck against the Roma striker's leg by Abate and the ball rebounded into the back of the net to break the deadlock and earn Roma all three points.