كتب : Mohamed Sabe
Alberto Gilardino opened the score for Milan but a penalty from David Suazo put the home side at level before the interval.
Andrea Capone grabbed the lead for Cagliari five minutes after the hour while Marco Borriello equalized four minutes later.
Milan were reduced to ten men in the 75th minute when Andrea Pirlo was given his marching orders.
The draw left Milan with in 15th spot with 12 points.
Elsewhere, Palermo were held to a goalless draw at Parma to settle in third place with 28 points.
In other matches, Fiorentina edged past Lazio with a 1-0 win, Livorno lost at home to Chievo 2-0, Torino beat Empoli 1-0, Reggina held Udinese to a 1-1 draw and Sampdoria won 2-0 at Messina.