The Chilean boss spent three years at the Etihad and won three major trophies — including a Premier League title in his first season.
Before moving to England, Pellegrini established himself as a top level boss following a successful ten-year period in Spain.
He established Villarreal as a relative force in Europe by leading them to the Champions League semi-finals and quarter-finals.
Pellegrini moved to Real Madrid in 2009 and signed the likes of Cristiano Ronaldo, Kaka, Karim Benzema and Xabi Alonso.
The 96 points amassed in La Liga that season were not enough to overhaul Pep Guardiola’s Barcelona who were crowned champions, finished on 99.
Pellegrini was ruthlessly sacked and replaced by Jose Mourinho after just one season at the Bernabeu.
He took over as boss of Malaga in 2010 and led the Spanish side to the Champions League quarter-finals two seasons later, beating the likes of Milan and Porto on the way to a heartbreaking defeat to eventual finalists, Borussia Dortmund.
Sinisa Mihajlovic was sacked as Milan boss midway through last season after a disastrous campaign.
Former player Cristian Brocchi was hired on an interim basis until the end of the season but could only lead the Rossoneri to shocking seventh-place finish and defeat in the Coppa Italia final