Ten-man Inter Milan hung on to beat crosstown rival AC Milan 1-0 on Sunday in a bad-tempered Serie A derby that saw the hosts have a goal disallowed and a late penalty appeal waved away as they chased an equaliser.
Walter Samuel headed Inter in front in the fourth minute following a howler from goalkeeper Christian Abbiati as the Nerazzurri's quick start seemed to surprise Milan.
Milan improved but had Riccardo Montolivo's goal disallowed for a foul on Inter goalkeeper Samir Handanovic.
Nagatomo sent off
Inter's chances of a third straight derby victory seemingly diminished when Yuto Nagatomo was sent off for a second yellow card shortly after the break.
Milan laid siege to the Inter goal but could not find the equaliser, despite going agonizingly close on several occasions. It was also denied what looked to be a clear-cut penalty late on when Robinho appeared to be brought down by Samuel.
"I have nothing to reproach the squad about tonight," said Milan coach Massimiliano Allegri, whose team is off to its worst league start in 72 years after losing four of its first seven games.
"I'm disappointed with the incidents that happened. I almost never talk about the referee, actually I never do, but tonight he was unlucky, he had an unhappy night. He made decisions only against us and he should have made decisions that he didn't. It was a match in which we were punished by the referee in the most astonishing manner. ... He also ruled out the goal and I don't understand why."
In a heated atmosphere, there were several calls over the speaker system for the fans to stay in their seats and behave themselves or risk the game being suspended.
Former Milan striker Antonio Cassano was roundly jeered throughout by the home support in his first match against his old club since his offseason switch to its bitter rivals.
There were also several banners negatively referring to Cassano's heart surgery last year.
However, Cassano seemed to revel in the atmosphere, at one point repeatedly raising his arms to encourage the fans to whistle more loudly as he strolled to take a corner.
"We still have a lot of things to work on but tonight was very positive," Inter coach Andrea Stramaccioni said.
"I was happy to see how the lads were on the pitch, they played more as a group."