Cristiano Ronaldo scored the winning goal for Juventus in the Champions League defeat to Manchester United, with a 2-0 win over AC Milan in 10 games, with Gonzalo Higuain missed a penalty before being sent off for the hosts was.
Mario Mandzukic gave the hosts the lead in the 8th minute at the San Siro, and Ronaldo netted his second goal in the 81st, with Juventus taking six points.
The reigning Serie A champions have defended their seven-time Serie A title after losing their first defeat of the season to United following a late double but Ronaldo's equalizer.
"The winning night was the only way to get what happened in the last five minutes of the Champions League," said Juve coach Massimiliano Allegri.
"It was important to win despite not conceding goals and getting six points in Napoli.
However, for the third time this season, AC Milan have dropped out of the Champions League in Lazio, who finished fourth, despite drawing 1-1 with Sassuolo.
Inter have won their last seven encounters with Atalanta, with Luciano Spalletti's side losing 2-0 to Napoli.
Juventus have 34 points from 12 games, six ahead of Napoli and Carlo Ancelotti with Inter three points behind.
"I am very happy, especially the club, because we play Milan is always difficult," Ronaldo said.
"It's important to win because Napoli beat Genoa at night and we have to keep track of our trip."
Allegri's side has rarely been hit by AC Milan, with Mandzukic increasing to return Alex Sandro to a massive 75,000-strong San Siro supporter.
The World Cup final would take about two minutes after scoring against Ronaldo, but AC Milan captain Alessio Romagnoli was arrested.
Higuain is back from a defensive crisis to meet with his parents, but it would be the former captain of the attack, who joined Milan on loan until last summer to take over at Real Madrid.
The Argentine missed a penalty when he was given the Medhi Benatia in the 5th minute, before giving the ball to goalkeeper Wojciech Szczesny.
Ronaldo tested Gianluigi Donnarumma at AC Milan early in the second half before scoring nine minutes after scoring his first goal for the San Siro.
After moments later, Higuain was sent off after scouting the referee after a mistake in Benatia, leaving the field.
"I said I was not overwhelmed, to be calm, and not a penalty," Ronaldo told Higuain.
"He was disappointed, he lost, but I did not blame, and he did not say anything."
– Inter –
At the beginning of Sunday, defender Gianluca Mancini scored his third goal for Atalanta to lead Milan to home to Bergamo.
Mancini put the opponent in the 62nd minute, after Hans Hateboer, Berat Djimsiti and Alejandro Gomez fired home three minutes from the hosts.
Inter captain Mauro Icardi equalized after penning a penalty, but his side ended the match with 10 men after Marcelo Brozovic was sent off for two minutes.
Roma have returned to winning ways with a 4-1 lead over Sampdoria to complete sixth, three points in the Champions League with Lazio and AC Milan.
Chievo, bottom of the league, drafted a 2-2 draw at Bologna to earn points on points, with three clear-cut chances.
But coach Gian Piero Ventura told his players to stop after the game, not believing he could save them from leaving the club.
In other news, Empoli have reached their first win since the beginning of the season, winning 2-1 at Udinese, who joined nine points.