Iker Casillas
Casillas is out-of-favour at Real Madrid (Reuters)

Real Madrid's interest in securing the services of Manchester United goalkeeper David de Gea is expected to increase even further after Iker Casillas exploded against his own fans whistles during La Liga's 2-2 draw against Valencia on Saturday (9 May).

The Spaniard's future at the Santiago Bernabeu has been under scrutiny in recent years since he fell out of favour with current Chelsea manager Jose Mourinho, with Real Madrid having identified De Gea as his replacement.

A number of the Real Madrid supporters have since expressed his disapproval with the club number one by whistling at him in a number of games during the last two campaigns.

Casillas has dealt with the scrutiny well until now, insisting that fans have the right to criticise the players.

But the Spanish international exploded against his own fans after a big part of the Santiago Bernabeu blamed him for the draw against Valencia that left Los Blancos' hopes to win La Liga all but ended – with Barcelona four points ahead with just two games remaining.

After being booed by the crowd every time he touched the ball during the first half, the keeper lifted his arm as a sign of irritation while was caught by Spanish TV station Cuatro saying: "F***k off."

"P*ss off. You are such a drag. F**k. F**k with the sh*tty whistling. F***k off. P*ss off. It's breaking my balls."

Click the link for what went down:

Casillas exploded against Real Madrid fansCuatro

Casillas has said a number of times during the season that he wants to stay at his childhood side until the end of his contract in summer 2017.

But the latest incident with his fans makes his situation at the La Liga giants uncertain, while increasing the speculation in the Spanish press about his summer exit, as well De Gea's potential move from Old Trafford to replace him.

While it is well-known Real Madrid has earmarked the United keeper as its top priority to replace Casillas, Cadena Cope claims that Los Blancos are eventually ready to let Casillas go this summer – although the keeper is not likely to leave unless the club pay the remainder of his contract.

And the Spanish radio station insists that if Casillas decides to stay, he will be on the bench next season while Real Madrid will try to sign De Gea to be the number one.