Kaka scored on a penalty kick in the 67th minute to salvage a point for Milan at the San Siro Stadium.
The match featured Ronaldinho's first start in a month, but he was substituted in the second half after having had little impact. David Beckham started and played the whole game for AC Milan.
Inter beat Lecce 3-0 on goals by Zlatan Ibrahimovic, Luis Figo and Dejan Stankovic. Figo had not scored a league goal since September 2007.
Ten-man Juventus moved into second place when Christian Poulsen scored in stoppage time for a 2-1 victory over Catania.