MILAN - Ronaldinho scored his first goal for AC Milan as Inter fell to their first defeat under José Mourinho.
The Brazilian headed Kaka's cross beyond Julio Cesar and into the top right corner on 36 minutes to seal a victory that leaves the Nerazzurri third in the table behind Lazio and Napoli.
The first half was an evenly balanced affair, with Inter's Mancini drilling wide and Maicon firing over before Kaka forced a good save from Julio Cesar.
Quaresma forced Abbiati into a tipped save, the Rossoneri keeper parrying Ibrahimovic's low shot moments later before Milan launched a counter-attack that resulted in Ronaldinho's opening goal.
With AC bossing the game in the early stages of the second half, José Mourinho made a double change, bringing on Adriano and Julio Cruz for Marco Materazzi and Mancini.
The tactical switch appeared to turn the game in Inter's favour but the Nerazzurri's task was made harder when Burdisso was sent marching for a second yellow in the 77th minute.
With time running out Mourinho made a further change, introducing Stankovic for Vieira. The Serbian almost grabbed a late equaliser, his well struck shot parried by Abbiati with Adriano narrowly missing with his follow-up shot.
Ancelotti responded by bringing on Shevchenko for Ronaldinho and the Ukrainian went close to increasing his team's lead a minute from time, forcing a splendid save from Julio Cesar with his blistering close-range shot.
AC Milan 1-0 Inter (HT: 1-0)
Scorer: Ronaldinho 36.
AC Milan (4-3-3): 12 Abbiati; 15 Zambrotta, 4 Kaladze, 3 Maldini, 18 Jankulovski; 8 Gattuso (25 Bonera 88), 23 Ambrosini, 10 Seedorf; 22 Kaka, 7 Pato (84 Flamini 74), 80 Ronaldinho (76 Shevchenko 84).
Subs not used: 1 Dida, 5 Emerson, 14 Cardacio, 77 Antonini.
Coach: Carlo Ancelotti.
Inter (4-3-3): 12 Julio Cesar; 13 Maicon, 16 Burdisso, 23 Materazzi (9 Cruz 59), 26 Chivu; 14 Vieira (5 Stankovic 80), 19 Cambiasso, 4 Zanetti; 77 Quaresma, 8 Ibrahimovic, 33 Mancini (10 Adriano 59).
Subs not used: 1 Toldo, 2 Cordoba, 24 Rivas, 45 Balotelli.
Coach: José Mourinho.
Referee: Emidio Morganti (Ascoli Piceno).
Booked: Gattuso 41, Jankulovski 51, Burdisso 61, 77, Vieira 66, Quaresma 69, Zanetti 83, Stankovic 85.
Sent off: Burdisso 77, Materazzi 83.