#4 Mo Johnston - Nantes to Rangers (1989)
Considering the history between two of the biggest Scottish clubs – Rangers and Celtic, a transfer of a player between the two clubs would not have even crossed anyone's mind in Scotland. The religious differences between the two Old Firm clubs made this derby unique than any other rivalry in the world.
Rangers had signed Catholic players unknowingly in the past, but it was in 1989, under Graeme Souness, that the Ibrox club embraced the idea.
Mo Johnston, a former Celtic player joined Rangers from the French club, Nantes. This move angered the Rangers fan base with the general secretary of Rangers' supporter's association saying, "It is a sad day for Rangers."
The club's kit man boycotted Johnston too and the player had to arrange his own kit before every game. He gradually won over the Rangers crowd by scoring 31 goals in one season.
#3 Alfredo Di Stefano - Millonarios to Real Madrid (1953)
One of Real Madrid's greatest ever player, Alfredo Di Stefano could have signed for FC Barcelona back in the 1950s. One can't even fathom the course of Spanish and world football had Di Stefano joined the Catalans instead of Real Madrid.
Di Stefano left for Colombian club, Millonarios in 1949 from River Plate. The Argentine club had claimed that they still owned the player which meant that Barcelona could strike a deal with them.
When this was happening in Argentina, Real Madrid agreed a deal to sign the striker from the Colombian club. Many conspiracy theories emerged after Real announced the signing of Di Stefano.
Spain's dictator, Francisco Franco forced Barcelona to sell all of their rights to Madrid, Franco's capital, was one of the theories that were doing the rounds at the time. This political rivalry known as the El Clasico took a whole new meaning after the conflict over the signing of Alfredo Di Stefano.
