4) Leonardo Bonucci
After a successful spell with Juventus, Bonucci secured a shocking move to AC Milan in 2017 even though some big clubs were looking for the defender.
The Italian regretted the decision within a few months after the club's terrible run of form. In spite of that, he is clearly among the top three centre-backs in the game at present.
The 30-year-old is reportedly eyeing an exit from San Siro in the upcoming transfer window. The defender would certainly find takers given his abilities.
Real Madrid have already been reported plotting a move for the player in the summer.
The player has at least three more years lying in front of him. Los Blancos should not let an opportunity to sign such a player let go off easily.