 He was surprisingly announced as new boss of last-placed Serie A team Cagliari on 27 December 2007, succeeding Sonetti, who ironically replaced him during his first period at the helm of the Sardinian side.Under his tenure as head coach, Cagliari dramatically improved their results, winning 32 points in 21 weeks, thus rising up the table and managing to escape relegation in advance of a week.However, Ballardini failed to find an agreement with Cagliari chairman Massimo Cellino for a contract extension, and they ultimately decided to part company on 28 May.