Casillas lost his place in the Real Madrid starting line-up under Mourinho. Reuters

Real Madrid legend Iker Casillas has admitted he had a tense relationship with Jose Mourinho during the Chelsea boss's tenure in La Liga.

Even though the Portuguese manager won a Copa del Rey and a La Liga title during three seasons at the Santiago Bernabeu, his term with the Spanish giants ended on a sour note after clashing with Real Madrid players –including Casillas and Ballon D'Or winner Cristiano Ronaldo.

Mourinho relegated Casillas to the bench despite the Spaniard being one of the club's biggest legends.

Two years later, the Spanish international keeper has finally broken his silence on the matter during an interview with Canal +, detailing his fraught relationship with Mourinho.

"Mourinho's time at Real Madrid was very good for us. I've always thought that. We were able to close the gap on Barcelona. The first season was very good, the last one, not so much. There everyone talks about things but that was a relationship that couldn't get anymore from it. I have complete respect for the coaches, but when there's something you don't like, you should talk about them. You should respect your boss," Casillas said.

Reports said Mourinho accused Casillas of being a traitor, providing private information to the press through his wife Sara Carbonero, one of the most famous journalists in Spain.

"We say that in this country, that has thousands of positive things, there are also some bad things. And one of these bad things is envy. It's true that for several months things looked pretty grim and everyone was to blame, that was the first problem. Everyone wanted to eradicate me like I was the plague", said Casillas.

"Maybe I should've spoken to him [Mourinho] and responded to Mourinho, but I opted to keep silent for the good of Real Madrid. A lot of people were on my case about keeping silent. I think what angers me the most is that the people thought I didn't care. We didn't have a good relationship and that's it. I decided to shut up. I'm not accusing anyone of anything or leaving anyone out to dry. What's normal, that in this case, is to talk."

According to some reports, Casillas, alongside Sergio Ramos, even demanded that Florentino Perez should sack Mourinho.

The keeper denies that and claims Mourinho has been one of the best managers of his careers.

"When we speak with the president, it's about the dressing room. We didn't speak about Mourinho to leave. For me, Mourinho was one of the two best managers I have had; daring, with character, then it came out that we pressured him to leave. It was false."