Fiorentina replaced Inter at the top of Serie A after ending the hosts’ 100 per cent start to the season in spectacular style at the San Siro.
Nikola Kalinic grabbed a hat-trick and Josip Ilicic also found the net for Fiorentina, who romped to a 4-1 win on Sunday, having led 3-0 inside 23 minutes in Milan.
Inter had defender Miranda sent off during a disastrous first-half, with skipper Mauro Icardi eventually pulling a goal back on the hour-mark.
Fiorentina also took the points in the corresponding fixture last season, having previously failed to win at the San Siro since 2000.
To compound a miserable night for Inter, they also lost in-form striker Stevan Jovetic who picked up a thigh strain during the warm-up.
City rivals Milan did not fare much better, as a deflected Blerim Dzemaili free-kick proved enough to condemn them to their third defeat of the season at Genoa.
Dzemaili’s effort found the net with just 10 minutes gone and Milan’s hopes of forcing their way back into the contest were not helped by a red card to defender Alessio Romagnoli just before the break.
Luiz Adriano and Mario Balotelli both went close for the visitors in the second half, but Sinisa Mihajlovic’s men could not find a way through and slipped to tenth in the table.
Torino, meanwhile, continued their fine start to the season with a 2-1 home victory over Palermo.
Giancarlo Gonzalez inadvertently gifted the hosts the lead with an own-goal just before the break, before Marco Benassi made it 2-0 three minutes into the second-half.
Gonzales then made amends for his earlier blunder by scoring at the right end to bring the Sicilians back into the game on 71 minutes, but Torino held on to secure their fourth win of the season.
Sassuolo remain fourth after being held to a 1-1 draw by Chievo, with both goals coming in the first-half at the Mapei Stadium.
Struggling Bologna remain in the relegation zone after slumping to a 2-1 home defeat at the hands of Udinese.
It was a very similar story at Hellas Verona who also took the lead only to lose 2-1 to Lazio.