Napoli matched Juventus with a 1-0 win over SPAL on Sunday to regain top spot in Italy from the champions who had earlier won the Turin derby by the same score.
The two Serie A pacesetters both bounced back from European setbacks to claim their ninth consecutive league wins.
Napoli — shocked 3-1 at home by RB Leipzig in the Europa League — stayed top with a narrow home victory at their San Paulo Stadium and injury-depleted Juventus — held at home by Tottenham in the Champions League — continued their derby domination of Torino 1-0.
Both clubs could thank Brazilians for the three points with Alex Sandro scoring the only goal for Juventus after 33 minutes and Allan putting Napoli ahead after just six minutes.
Napoli have 66 points after 25 games with Juventus one point behind. AS Roma moved third 15 points behind the top two with a 2-0 win at Udinese Saturday as Inter Milan fell back into crisis with a 2-0 loss in Genoa.
Luciano Spalletti's side, who were top of Serie A two months ago and unbeaten until December 16, are now fourth and could fall to fifth if Lazio beat Verona on Monday.
In the battle for European places Sampdoria, in sixth, travel to AC Milan, just below them, later on Sunday.
In Naples, Lorenzo Insigne hit the post after four minutes before Allan broke through after good work by Jorginho and Jose Callejon.
Callejon was denied a second by Pepe Reina who also cleared a Federico Viviani long-range effort.
Marek Hamsik looked to have scored a second after 63 minutes but he was ruled offside by the video assistant referee (VAR).
It was a new club record of nine consecutive league wins for Napoli.
Maurizio Sarri has insisted that Napoli's focus this season is a third Serie A title and first since 1990.
HIGUAIN INJURY BLWO
In Turin, the six-time defending champions dominated despite injuries and losing top scorer Gonzalo Higuain to an early knock.
Juventus were without injured Mario Mandzukic, Blaise Matuidi and Juan Cuadrado, with Paulo Dybala and Federico Bernardeschi starting on the bench.
Dybala made his comeback from a hamstring injury in the second half.
"Juve are a strong side with extraordinary players that for years has been challenging in all fronts and I don't consider the 2-2 with Tottenham to be a tragedy," said Allegri.
"I'm proud of the lads and today we saw a good reaction, we enjoyed ourselves even during difficult moments.
"We will go to London convinced we can do it," said Allegri.
With tensions already running high in the traditional "Derby Della Mole" the visitors were reeling after three minutes when Higuain landed awkwardly on his ankle as he rushed to pick up a Miralem Pjanic cross. The Argentine played on from another 12 minutes before being replaced by Bernardeschi.
Torino had an early chance with Joel Obi and Andrea Belotti two on one against Juventus centre-back Daniele Rugani but Belotti failed to control the ball.
Douglas Costa then burst down the right, his cross found Kwadwo Asamoah for a low volley that was cleared off the line by Nicolas N'Koulou of Torino.
A Belotti volley from a Iago Falque cross went into the side-netting with Juventus goalkeeper Wojciech Szczesny, replacing rested Gianluigi Buffon, stopping a Lorenzo De Silvestri header mid air.
Dybala came on in place of Douglas Costa after 66 minutes and the Argentine almost doubled Juventus' advantage immediately, picking up a perfect assist from Bernardeschi, but failing to finish off.
The win was an 18th for Juventus in the last 24 Turin derbies, with Torino sitting ninth, five points off the European places.
Elsewhere bottom side Benevento claimed just their third win of the season coming back from a goal down to beat Crotone 3-2, as Bologna, in 13th, beat relegation-threatened Sassuolo 2-1.