Christian Pulisic fired AC Milan to derby victory with the only goal in Sunday's 1-0 win over Inter Milan, moving his side up to second in Serie A and within two points of new leaders Roma.
USA forward Pulisic pounced for his fifth goal of the season in the 54th minute after Inter goalkeeper Yann Sommer weakly palmed away Alexis Saelemaekers' low shot, Milan's only true opportunity of a tense encounter at a boisterous San Siro.
Pulisic has been excellent this season, with two assists to go with his joint league-leading goal tally for Milan, who have a great record against the top teams but have dropped points to the lesser lights.
"Often you're more on it for a big match, and we need to understand that we're vulnerable when we let the intensity drop," said Milan coach Massimiliano Allegri.
But Milan also had Mike Maignan to thank for the three points as the France goalkeeper kept out Hakan Calhanoglu's penalty in the 74th minute and tipped a Lautaro Martinez volley onto the post eight minutes before halftime.
Francesco Acerbi thumped a header onto the woodwork 10 minutes before as Inter dominated the play but couldn't find their way past Maignan.
Inter sit fourth, a point behind Milan and champions Napoli, and narrowly above high-flying Bologna.
Cristian Chivu's team now turn their attentions to Wednesday's Champions League clash at Atletico Madrid, where they can take another step towards direct qualification for the last 16 after winning all four of their previous matches.
"We're on the right track. We believe in the coach and the project, and we can't change our minds about that because of one defeat," said Marcus Thuram.
"We've got things we need to improve, but we can't throw everything out the window."
Milan meanwhile have a whole week to bask in a second straight derby win, with the red and black half of the city not having tasted defeat to their local rivals since Inter sealed their 20th league title against them in April 2024.
Earlier, Matias Soule, Evan Ferguson and Wesley scored the goals which gave Roma a 3-1 win at Cremonese and continued their strong start to life under Gian Piero Gasperini.
ROMA LEAD THE WAY
Roma had only scored 12 times in their previous 11 league fixtures but were clinical in front of goal at the Stadio Giovanni Zini and are in the discussion for a first league title since 2001.
"I said yesterday that it's only right to dream in these positions, even though in the end dreams rarely come true," said Gasperini.
"We're trying to keep the dream going for a little while longer."
Soule fizzed in Roma's opener in the 17th minute, just after Cremonese forward Federico Bonazzoli had forced a fine save from Mile Svilar.
And what had been a tight match was then decided by two quick strikes from Brighton loanee Ferguson, who scored his first club goal in over a year, and Wesley.
Ferguson calmly stroked home in the 64th minute after the ball rattled around the Cremonese area, and moments later Brazilian full-back Wesley finished off a lightning counter-attack by dinking a brilliant finish over Emil Audero.
Prior to Roma making the game safe, centre-back Gianluca Mancini was spared from conceding a penalty near halftime after a VAR check chalked off his penalisation for handball.
And Gasperini, who was livid with the initial awarding of a penalty against Mancini, was sent off for more dissent shortly before Ferguson doubled Roma's lead.
That means Gasperini will miss Roma's huge clash with champions Napoli in the Italian capital next weekend.
Gasperini was seen going berserk with joy in the stands after Ferguson broke a club goal duck which stretched back to October last year.
The 21-year-old was only fit for the bench and with Paulo Dybala and Ukraine striker Artem Dovbyk both sidelined with injury the Ireland international's goal is great news for Roma.
Francesco Folino netted a consolation goal in stoppage time for promoted Cremonese, who sit 12th after their fourth defeat of the season.