Luca Toni scored the winning goal 18 minutes from time as Roma beat champions Inter 2-1 at the Stadio Olimpico here on Saturday to reignite the Serie A title race.
Roma's win means they move to within a single point of the leaders and AC Milan could join them if they beat Lazio on Sunday.
Daniele De Rossi opened the scoring for Roma in the first period but Diego Milito equalised after the break before Toni's potentially crucial winner.
The result means that Claudio Ranieri's team have clawed back 13 points on Jose Mourinho's men since the two clubs last met back in November, while Mourinho will count the cost of seven bookings that will see four of his players suspended next week.
Ranieri acknowledged that the title race will now go down to the wire with seven games left.
"Today we beat a stratospheric team," he said. "It will be a great battle of nerves, now we're in the final straight. We're in good shape and the players believe in themselves.
"I'm already thinking about our next match against Bari. Every game will be difficult and we need to be humble and focussed, as we were tonight."
As expected for a top of the table clash there was a cagey opening in the capital and it took a mistake from Inter goalkeeper Julio Cesar to break the deadlock in the 17th minute.
Nicolas Burdisso sent a weak header into the Brazilian shot-stopper's hands from David Pizarro's free-kick but Cesar spilled the ball and De Rossi acted quickly to slide in and poke home the rebound.
That sparked an immediate response from the champions and Wesley Sneijder lashed a 30-yard free-kick just wide.
Inter started to look more like the Serie A leaders and they produced a neat move on 22 minutes involving Thiago Motta, Samuel Eto'o and Dejan Stankovic, who dragged his shot wide.
The hosts matched what the visitors threw at them, though, and another slick passing move at the other end resulted in Mirko Vucinic's curling effort being deflected wide.
Roma's Norwegian left-back John Arne Riise then thumped a rasping free-kick from 25 yards that swerved inches past the post and Vucinic forced Cesar to sprawl to his right to palm away another fierce shot from a clever free-kick routine.
Inter almost levelled four minutes before the break as Walter Samuel rose on the edge of the six-yard box to head Sneijder's corner powerfully goalwards only to see the ball crash down off the bar.
And Inter began the second period by hitting the woodwork again as Milito's shot was deflected onto the corner of bar and post.
The leaders were fired up and moments later Sneijder brought a fine save out of Julio Sergio, while at the other end Toni flicked a header just over the bar.
Mourinho threw on a third striker in former Lazio forward Goran Pandev and the game opened up further, with Sneijder ramming a shot down Sergio's throat before Riise blasted high and wide.
Inter equalised 24 minutes from time as Sneijder crossed for Milito to prod home from inside the six-yard box, although television replays showed there had been an offside in the build-up.
But just as Inter looked to be taking control, a miscued shot from substitute Rodrigo Taddei fell to Toni, who shot home into the bottom-right corner from 15 yards on 72 minutes.
Inter threw everything at Roma and came within inches of equalising deep into injury time when Milito crashed a shot against the left-hand upright.