Sir Alex Ferguson paid homage to Jose Mourinho as the Roma manager joined an exclusive club of managers.
Mourinho, 58, will take command of his 1000th game on Sunday night when Roma hosts Sassuolo in Serie A.
His illustrious resume includes two Champions League victories as well as domestic titles in his native Portugal, England, Italy, and Spain, and he is widely considered as one of the best coaches of all time.
Ferguson, a Manchester United icon, agreed with this assessment and congratulated Mourinho on his induction into the League Manager Association's (LMA) Hall of Fame 1000 club.
"Reaching 1000 matches as a manager will be such a proud day for both Jose and his family and rightly so," the Scot told the LMA website.
"To reach this landmark as a manager is an outstanding accomplishment for Jose, particularly whilst excelling and winning titles in four European leagues and of course winning two Champions League trophies along the way.
"Jose's achievements will always ensure that he is acknowledged as one of the managerial greats. On behalf of the League Managers Association, congratulations and welcome to the Hall of Fame 1000 Club, Jose."
Mourinho rose to prominence with Porto, winning five major titles in two seasons before taking over as manager of Chelsea in 2004.
He guided the Blues to back-to-back Premier League championships, the FA Cup, and the League Cup in 2004/05, and his team allowed a record-low 15 goals.