#4 Aad De Mos (KV Mechelen)
In the reversal of the usual football manager's career path, De Mos went from a giant club to a tiny one. After winning 2 titles at Ajax by the tender age of 35, De Mos took charge of Belgian minnows KV Mechelen in 1986.
At that time Belgian football was dominated by the likes of Standard Liege and Anderlecht whereas Mechelen had just been promoted from the second division.
However, backed by an electronics millionaire, Mechelen brought in Israeli winger Eli Ohana and legendary goalkeeper Michel Preud’homme from domestic rivals Standard Liege.
As a result of the investments, Mechelen managed to win the league in the 1988/89 season conceding just 62 goals in 102 league games during 3 successful years.
Perhaps more surprisingly, the Belgian side managed to win the European Cup Winners Cup in 1988 beating his former employees Ajax in the final. No Belgian side has laid hands on a European trophy since.