Marco Borriello put the visitors ahead after 20 minutes but his team saw their one-goal advantage overturned.

Antonio Cassano leveled the score on 54 minutes before Giampaolo Pazzini scored the winner for Sampdoria in the last minute.

Third-placed Milan are now seven points adrift of leaders Roma, six of city rivals Inter who lie second in the league table.

Roma beat Lazio 2-1 on the same day.