AC Milan inflicted a first defeat of the season on rivals Inter Milan with a 3-1 win in a derby thriller on Saturday, as Roma cut the gap to first place to one point.
Christian Pulisic and Adrien Rabiot struck inside the opening 10 minutes to get the Rossoneri off to a dream start before Alessandro Bastoni pulled one back.
An inspired Diego Moreira proved to be Milan's hero as the Belgian, having assisted the first two goals, swept home a free-kick late in the first half to restore a two-goal cushion as Ruben Amorim's side responded well to suffering their first league defeat of the season at home to Bologna in midweek.
"The environment is amazing," Amorim told DAZN. "The passion is completely different from any derby I have played."
"I'm really happy for the players. It was important. The fans gained a little bit more confidence in the project. We are going to have amazing nights like today and we are going to have nights like Bologna, that is part of the process."
Milan's victory stretched their unbeaten record in the famous fixture to eight games as Amorim's side moved into fourth place, four points off Inter and Lazio on top.
Roma's 5-2 win at Udinese moved them one point behind Inter in third.
Two days after plans were revealed for both clubs to move into a new stadium in 2031, the iconic 100-year-old Stadio Giuseppe Meazza was at its atmospheric best for AC Milan's 'home' game.
Milan looked fired up from the first whistle as they raced into an early lead, Pulisic heading home an inviting Moreira cross inside four minutes in the week the American signed a five-year contract extension with the Rossoneri.
Moreira was the architect again when Milan doubled their lead, fizzing a corner into the path of Rabiot, who swept a clever finish through a crowded box and in off the far post.
Inter hit back with a corner of their own midway through an electric first half when Bastoni nodded in from close range.
The goal sparked a period of dominance from the Nerazzurri, but they could not beat an inspired Mike Maignan, who produced a sharp save on Hakan Calhanoglu before an outstanding one-handed reaction stop denied Djed Spence what had seemed a certain goal.
With Inter in the ascendancy, Milan hit back against the run of play when Moreira curled a free-kick over the wall and into the top corner two minutes before the break.
The frenetic nature of the game calmed in the second half as a cagier affair unfolded, Inter probing to get back in the game as Carlos Augusto headed wide from a promising position.
An incorrect decision to award Inter a penalty for handball was overturned following a VAR intervention as the Nerazzurri were left frustrated in their hunt for another goal, Milan substitute Alphadjo Cisse instead coming closest late on with a curling strike that required a flying save from Josep Martinez.
ROMA REDUCE GAP
Roma blew away struggling Udinese with a rampant first-half display to claim a 5-2 away win and move one point off top.
Gian Piero Gasperini's unbeaten side moved up to 24 points, one behind joint-leaders Inter and Lazio, who can pull clear on top when they host Cagliari in Rome on Sunday.
Bryan Cristante, Rodrigo Mora, Donyell Malen and Evan Ndicka all struck before halftime and the woodwork twice denied the visitors in a dazzling show of attacking force.
Nicolo Zaniolo scored against his former club and Matteo Palma struck with a volley as Udinese improved after the break, but Daniele Ghilardi made it five in stoppage time to leave the hosts in 19th on five points after an eight-match winless run.
Earlier, Bologna claimed a third consecutive win to climb into eighth place as they came from behind to beat Monza 2-1.
League top scorer Gustavo Varela bagged his ninth goal of the season from the spot to put the visitors in front, but Tommaso Pobega and Federico Bernardeschi hit back before Bologna goalkeeper Lukasz Skorupski saved a late Patrick Cutrone penalty.