Real Madrid coach Jose Mourinho shouts to his players during their Spanish King's Cup final soccer match against Atletico de Madrid at Santiago Bernabeu stadium in Madrid, May 17, 2013. [Photo/Agencies]

However, the determining factor has been his deteriorating relationship with Casillas, who has not played since recovering from a broken finger he suffered in late January. Mourinho preferred Diego Lopez, who was signed from Sevilla to cover for the Spain international and recently said Casillas would not be first choice again while he was at the club.

Most put this decision down to the bad relationship between the pair, although Casillas' journalist girlfriend, Sara Carbonero certainly did not help matters when she announced on Mexican TV there was a bad relationship in the club dressing room.

As well as losing to Atletico in the Spanish Cup, Real Madrid lost in the semifinals of the Champions League to Borussia Dortmund and are 11 points behind FC Barcelona in the Primera Liga with just two game left to play.

Speaking after the Cup defeat on Friday, Mourinho said that although many clubs would be pleased with these achievements, it was the worst season he has had as a club coach.

Although he will now stand for re-election as club president in elections which he confirmed will be held on July 16, Florentino Perez must take some of the blame for Mourinho's failure at Real Madrid. Perez allowed Mourinho increasing powers over Mourinho's spell, dispensing with the services of director of sport, Jorge Valdano, who has influence over signings, doing nothing to curb Mourinho's more controversial moments and allowing such a bad atmosphere to build up around the club.

Since sacking the current Spain coach, Vicente del Bosque at the end of the 2002-3 season, Real Madrid have won just four trophies in seven seasons with Perez as President (Ramon Calderon was club President from 2007-2009) - Two Spanish Supercups, one Spanish Cup and one league title. Meanwhile the club has invested over 500 million Euros in signing players such as Cristiano Ronaldo, Kaka, David Beckham, Luka Modric, Karim Benzema, and etc.

Mourinho will now almost certainly return to Barclays Premier League club, Chelsea, where he enjoyed considerable success, winning two Premier League titles, the FA Cup and two League Cups between June 2004 and September 2007.

Paris Saint Germain coach, Carlo Ancelotti looks likely to replace Mourinho after it was confirmed he has asked to leave the French club. However, Paris want Ancelotti to see out the remaining year on his contract and Madrid may have to pay compensation in order to bring the experienced Italian coach to Spain.