Defending champion Juventus scored a stoppage-time winner to beat Bologna 2-1 on Wednesday and extend its unbeaten Serie A run to 49 games.
Paul Pogba headed in the winner to cap an excellent game from the young midfielder, who showed exactly why Manchester United was so desperate to keep him before his move to Italy in the off-season.
Fabio Quagliarella put Juventus in front in the 54th minute, but Bologna midfielder Saphir Taider levelled in the 71st.
Juventus is four points ahead of Inter Milan after Andrea Stramaccioni's side recorded its sixth succesive victory, beating 10-man Sampdoria 3-2.
It sets up a mouthwatering clash between the two bitter rivals this weekend.
Napoli has now fallen below Inter after losing 1-0 at Atalanta. Carlos Carmona scored in the 64th minute to inflict Napoli's second defeat of the season.
Juventus approaching record
Juventus is closing in on Milan's record of 58 Serie A games unbeaten, set over the 1990-91, 91-92, and 92-93 seasons.
The home side thought it had taken the lead in the 13th minute but Pogba's header was ruled out for a push on Marco Motta. Pogba again went close with a 30-yard effort that crashed off the upright.
Bologna also had a goal ruled out in the 18th minute when Manolo Gabbiadini — who is on loan from Juventus — headed in but it was disallowed for a handling offence.
Nicklas Bendtner almost gave Juventus the lead five minutes from halftime with a powerful effort from more than 30 yards that goalkeeper Federico Agliardi did well to turn round the post.
Pogba then headed an Andrea Pirlo free kick wide from close range.
Juventus took a deserved lead nine minutes into the second half when Emanuele Giaccherini headed Pogba's lob on for Fabio Quagliarella to head in.
However, Taider scored against his parent club with a perfectly placed shot from the edge of the area, which brushed the outstretched hand of Gianluigi Buffon before going in off the post.
However, Pogba was soon on hand to head in Sebastian Giovinco's header.
In Milan, Inter gifted Sampdoria the lead in the 20th minute when Andrea Ranocchia and Walter Samuel got in a mix up with what should have been a fairly straightforward free kick to clear and the ball was bundled in by Gianni Munari.
Inter levelled six minutes into the second half when Andrea Costa was dismissed for bringing down Diego Milito in the area and the Argentina striker stepped up to fire in a penalty off the inside of the right post.
Milito went close to putting Inter ahead on the hour mark but hit the left post.
Inter took the lead when Antonio Cassano — who spent three and a half seasons at Sampdoria — raced from the halfway line to the edge of the area before setting up Rodrigo Palacio, who fired into the bottom left corner.
Fredy Guarin sealed the result eight minutes from time before Eder scored another goal for Sampdoria in stoppage time.
Lazio is nine points behind Juventus after being held to a 1-1 draw at home by Torino.
Kamil Glick headed Torino into an early lead but Stefano Mauri levelled shortly before the hour mark.
Roma slipped further down the table after a second successive defeat, a 3-2 loss at Parma.
The capital side took the lead in the eighth minute when Erik Lamela scored his fifth goal in four games — and his sixth of the season.
But Ishak Belfodil, Marco Parolo and Cristian Zaccardo all scored for Parma before Roma was awarded a penalty. Francesco Totti saw his spotkick saved but fired in the rebound.
Elsewhere, Cagliari got off to a great start on its way to a 4-2 victory over rock-bottom Siena.
A double from Nene and a goal from Marco Sau saw the home side take a 3-0 lead with less than half an hour gone. Siena's Emanuele Calaio saw his penalty saved before Erjon Bogdani reduced the deficit before halftime.
Neto was sent off for a second yellow card. Thiago Ribeiro and Calaio scored in the dying minutes.
Antonio Di Natale scored twice — one a penalty — as Udinese drew 2-2 against Catania. Lucas Castro and Francesco Lodi scored for Catania.
Chievo beat Pescara 2-0 with a penalty from Luciano and a goal from Adrian Stoian.
Pescara played almost an hour with 10 men after Simone Romagnoli was sent off for hauling down Cyril Thereau
The match was paused for a few minutes late on as fierce winds blew hoardings onto the pitch. The players helped carry them off.