Two goals by AC Milan forward Rafael Leao helped the defending champions fight back from a goal down and earn a 3-2 win over local rivals Inter Milan on Saturday in their fifth Serie A match of the season.
The victory briefly sent Milan top of the table before Napoli leapfrogged them with a 2-1, come-from-behind win at Lazio.
Inter midfielder Marcelo Brozovic scored his first Serie A goal of the season in the 21st minute after an assist by forward Joaquin Correa following a brilliant counterattack orchestrated by forward Lautaro Martinez.
Milan levelled seven minutes later through forward Rafael Leao, who slotted home past Inter keeper Samir Handanovic after collecting a pass from Sandro Tonali.
Stefano Pioli's side kept pressing but spurned a host of chances before the halftime whistle.
Milan forward Olivier Giroud completed the comeback in the 54th minute with a weak shot that did just enough to beat Handanovic.
Leao scored his second goal after swiftly moving past the Inter defence and firing home in the 61st minute to extend the lead.
"Rafa has beautiful moves, plays beautifully, knows he has talent," Pioli told reporters.
Inter did not go down without a fight, however, and scored just seven minutes later through forward Edin Dzeko, whose strike bounced off the post and slipped in.
Milan keeper Mike Maignan delivered a superb performance, keeping out further efforts by Inter who kept pressing until the end but were denied an equaliser.
"We conceded three goals, something you cannot afford in a derby. For the chances we had we should have deserved a draw," Inter manager Simone Inzaghi told reporters.
"We struggled a lot to score two goals this evening, and then we found in front of us a great goalkeeper."
Pioli also said Milan should be grateful to Maignan for not conceding another goal.
"Until the 70th minute I liked the team a lot, they played with courage and fought with great determination," he added.
Milan are second in the table on 11 points after five games and travel to Sampdoria next Saturday while Inter, sixth on nine points, host Torino on the same day.
Napoli jumped back above Milan into top spot with their win away at Lazio.
The home side scored an early opener through Mattia Zaccagni, but Luciano Spalletti's side fought back and turned the match in their favour with goals by Kim Min-jae and Khvicha Kvaratskhelia.
"Overturning this match becomes a shortcut for our growth to speed up and soar," Spalletti told reporters afterwards.
Summer signing Kvaratskhelia has been involved in five Serie A goals, more than any other player at the club in his first four appearances as a starter since Napoli returned to the Italian top-flight from the 2007-2008 season.