Juventus, chasing a seventh successive title, played first, won and briefly went top only to be pulled back by their rivals Napoli.
Napoli stayed one point ahead of Juventus at the top of Serie A on Sunday after both teams won their ninth league games in a row, this time beating SPAL and Torino 1-0 respectively.
Napoli captain Marek Hamsik thought he had scored a second, was booked for smashing into the corner flag and, to add insult to injury, saw the goal chalked off by the video assistant referee (VAR) after a two-minute delay.
In the later game, AC Milan missed a penalty and had a goal ruled out by VAR in a 1-0 win over Sampdoria which extended their unbeaten run to 10 matches in all competitions.
The pattern at the top was the same as the previous three weekends when Juventus, chasing a seventh successive title, played first, won and briefly went top only to be pulled back by their rivals.
Juventus will also play first for the next three rounds of matches, a situation which has drawn complaints from Napoli coach Maurizio Sarri.
Brazilian midfielder Allan finished off a typically incisive Napoli move to score the only goal in the sixth minute at rain-soaked San Paolo stadium.
Hamsik's second-half goal was ruled out for offside and, although replays showed it was the right decision, the incident raised more questions about the use of the video technology being trialled in Serie A, among others, this season.
Napoli's stadium announcer, known as "Decibel Bellini" had gone through his entire ear-splitting celebratory routine and relegation-threatened SPAL were ready to kick off before the referee signalled that he was reviewing the goal.
Napoli have 66 points from 25 games with Juventus on 65 and AS Roma a huge 15 behind in third place.
Juventus overcame an early injury to striker Gonzalo Higuain as they bounced back from their disappointing 2-2 draw at home to Tottenham Hotspur in the Champions League to edge their less glamorous neighbours in the Derby della Mole.
"This was not a response (to the Tottenham game). Today, we produced a great performance and I'm proud of the lads and to coach this group," said Juventus coach Massimiliano Allegri.
Higuain appeared to twist his ankle and soldiered on for another 10 minutes before being replaced by Federico Bernadeschi, who set up the goal when he pulled the ball back for Alex Sandro to tap in just after the half hour.
Juventus have won seven and drawn one of their last eight matches against Torino.
Milan midfielder Giacomo Bonaventura sidefooted the winner from Davide Calabria's cross after 13 minutes in an eventful game at San Siro.
The hosts, who pulled level on 41 points with sixth-placed Sampdoria, could have gone ahead earlier but Ricardo Rodriguez's weak penalty was saved by Emiliano Viviano.
Leonardo Bonucci thought he had added a second before halftime until VAR intervened. Milan had celebrated and Sampdoria were ready to restart when the decision was finally made, but replays showed that it was clearly offside.
Table-propping Benevento twice came from behind and then beat Crotone with an 89th minute goal by Cheick Diabate, the Malian scoring 12 minutes after coming on for his debut following his move on loan from Osmanlispor.
Benevento stayed bottom with 10 points while Crotone have 21, four above the relegation zone.
Erick Pulgar scored with a long-range free kick in the 88th minute to give Bologna a 2-1 win over Sassuolo in the day's other game.
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