De Gea thinks every aspect of his game has improved since he moved to Old Trafford. “I have been here for four years now and I think that every aspect of my goalkeeping has improved,” De Gea told ManUtd.com. “It is hard to single out one area because we have worked and improved on everything. “I think the fact that I have started to do interviews in English has really helped as well, it has helped me to learn more of the language as well.” Despite his recent displays, De Gea thinks he can still improve. “Again, no matter how excellent your form is, you can always get better and there are always aspects of your game that you can improve,” he said. “You can improve everything. No matter how well people think you are playing, or how well you think you are playing yourself, it is always a case of working on every facet of your game. There is hopefully more to come.” Such has been De Gea’s form, that Real Madrid have become interested in signing the 24-year-old as a replacement for Iker Casillas. De Gea has 18 months left on his United contract, but the club are confident the goalkeeper will remain at United despite interest from the 10-time European champions. David de Gea says he felt like comic book super hero Captain America following his remarkable transformation from skinny youngster to hulking goalkeeper. Press Association Much was expected of De Gea when he signed for Manchester United from Atletico Madrid in 2011, but the then 20-year-old struggled for form straight away, making several costly errors. The teenager’s scrawny, gangly frame did not help matters. The Spaniard was unable to deal with the physicality of the Barclays Premier League and his confidence was low as a result. Fast-forward three and a half years and De Gea has turned into one of the best goalkeepers on the planet, thanks partly to a more robust physique, which he attributes to a strengthening programme he embarked upon shortly after joining United. So impressed was the Spain international that he likened his transformation to that of Marvel comic book character Steve Rogers, a weak Irish immigrant who morphed into muscular soldier Captain America after taking a serum administered by the US Army. “I was like Captain America in one year,” De Gea said with a smile on United’s website. “I still do the programme, although not as much as before. “It is more of a reduced programme now but certainly I did a lot of gym work at the start and it did have a big impact.” De Gea has saved United on several occasions this season. His latest goalkeeping master class came on Sunday when he kept Tottenham at bay in the 0-0 draw at White Hart Lane. At the end of October the former Atletico Madrid stopper won United all three points against Everton with fine saves to deny Bryan Oviedo, Leon Osman and Leighton Baines from the penalty spot.