Inter Milan moved four points clear at the Serie A summit with a 1-0 win over arch rival Juventus in the Derby d'Italia.
After a ferocious first half, it took a 72nd-minute goal from Sulley Muntari to decide the game in the home side's favour.
Jose Mourinho prevailed in the much-anticipated battle of two former Chelsea coaches against Claudio Ranieri and saw his side cement its place on top of the table.
Mourinho recalled Adriano to his starting line-up after overlooking the Brazil frontman for five matches due to a disciplinary matter.
Inter appeared to get lucky in the 24th minutes when referee Nicola Rizzoli waved away Juve's claims for a penalty after Muntari looked to have impeded Marco Marchionni inside the area.
He earlier denied the hosts a spot-kick in the first minute when Zlatan Ibrahimovic's cross struck the arm of Giorgio Chiellini at point-blank range.
Juve lost midfielder Tiago to a suspected serious knee injury after only four minutes.
Claudio Marchisio replaced him and he had Juve's only other effort of the first half two minutes before the break when Julio Cesar tipped his shot over the crossbar.
The rest of the first 45 minutes belonged to the Nerazzurri, who had three excellent opportunities to go ahead.
Dejan Stankovic had the first after 12 minutes when he broke the offside trap, but he was never able to get the ball fully under control as Cristian Molinaro and Chiellini both stopped him in his tracks.
Ibrahimovic was the next to break, capitalising on an error by Nicola Legrottaglie on the halfway line.
With his head down, the Swedish striker made like a train for the Juventus goal, leaving Legrottaglie in his wake before shooting just wide of the far post.
And Muntari had a header from Adriano's cross touched past the post by the leg of Juve goalkeeper Alex Manninger, who also touched a cross-shot from Adriano wide of the post and parried another Muntari effort in stoppage time.
The Bianconeri took the sting out of Inter in the second period.
When the home side did break through, Ibrahimovic fired another free shot wide of the post.
A touch of fortune enabled the Swede's next mis-hit shot to reach Muntari, who put the home side ahead in the 72nd minute. The Ghana midfielder was on hand to pass the ball into the unguarded net.
Juve's response was a header from Alessandro Del Piero which Julio Cesar clawed off the goal line, but the visitors could not muster anything else as their seven-game winning run was ended at the San Siro.
They saw Inter pull six points away, but could have few arguments after doing too little over the 90 minutes to deserve anything else.
In the other match, Fiorentina produced a fantastic second-half comeback to beat Udinese 4-2 in an action-packed encounter at the Stadio Artemio Franchi.
The Bianconeri had taken a first-half lead through Antonio Floro Flores before Adrian Mutu levelled from the penalty spot early in the second period.
Riccardo Montolivo scored a brace before Alberto Gilardino made it 4-1 for the hosts.
Antonio Di Natale pulled a late goal back from the penalty spot after Gianluca Comotto was dismissed.
Fiorentina 4 (Mutu 51p, Montolivo 63, 77, Gilardino 79)
Udinese 2 (Flores 29, Di Natale 83p)
Inter Milan 1 (Muntari 71)
Juventus 0