Carlo Ancelotti
Carlo Ancelotti refuses to rule out the signing of a goalkeeper. Reuters

Real Madrid manager Carlo Ancelotti has added fuel to the flames of speculation over the future of Manchester United star David de Gea by revealing the possibility of signing a new goalkeeper – even though he insisted Iker Casillas will stay at the Santiago Bernabeu until the end of his career.

Casillas's future at the Champions League winners has been under scrutiny since current Chelsea manager Jose Mourinho relegated him to the bench in favour of Diego Lopez. After rotating with Lopez last season, the Spanish legend has regained the starting spot with Ancelotti despite the summer arrival of World Cup sensation Keylor Navas.

But some fans at the Santiago Bernabeu believe the 33-year-old's best times are over and have whistled at him during a number of games this season, prompting speculations over his summer exit.

Real Madrid are indeed said to be in the market for a new goalkeeper and have reportedly earmarked de Gea as their main target, with the United star's contract at Old Trafford set to expire in summer 2016.

While Casillas recently revealed his intention to stay, Ancelotti had also always tried to play down all the rumours about his departure by claiming that he wanted the Spaniard at Real Madrid next season.

However, during an interview with ES Radio, the former Chelsea boss revealed for the first time the possibility of signing a keeper to be the number one ahead of the Spaniard.

Questioned if it is likely that another goalkeeper could be signed, he responded: "It's possible". Asked whether a new keeper means Casillas will be dropped, he said: "If a better goalkeeper comes along, then probably Casillas will not be [the first choice anymore]."

Nevertheless, Ancelotti insist he hopes Casillas to stay. "I don't think [he will leave]. I think he has a clear idea about his future. I'm sure that he will stay at Madrid until the end of his playing career. He's a veteran player and he knows the importance of treating the fans how they should be treated".

The Real Madrid manager admits that Casillas has been far from his best in some games in recent times, and when asked about the whistles from his own fans, he said: "It's very strange that the Bernabéu whistles at a player who doesn't deserve it."

"We have been whistled at many times and a lot of the time we did deserve it. Iker has faced the wrath of the fans but making mistakes is normal in football and he has accepted it without problems. It's more complicated to understand it when there is no motive".

Ancelotti believes the Spaniard has not regained his best form and deserves to continue as the number one.

"Casillas is currently in a good form, he seems motivated and relaxed to me. He has a strong personality. I can't say that Keylor Navas is our second choice keeper because I rotate the goalkeeping position now and again. I have confidence in both of them. If Casillas was out of form, I wouldn't field him.

"Last season, when he didn't play, that was down to a decision by the coach, not the board or the club. I just see the training sessions and decided who play. My job is far simpler than people think; the hard part is explaining to those who don't play why they are excluded. In Italy, they'd say that [Silvio] Berlusconi would send me the line-up by e-mail so I'm used to all of the gossip that's said".