David de Gea
De Gea has been United's outstanding performer of the season Getty Images

Manchester United goalkeeper David de Gea's future at Old Trafford continues to grow increasingly uncertain after the club clinched the signing of former Barcelona stopper Victor Valdes on an 18-month deal.

The three-time Champions League winner has been a free agent since last summer after Monaco withdrew from a deal to sign the Spanish international following his departure from the Nou Camp.

Valdes' experience gives United arguably the best goalkeeping combination in world football however the move, the first made by manager Louis van Gaal in the January transfer window, has swelled scrutiny over the future of de Gea.

The 24-year-old has been the club's most consistent performer this season and has won their player of the month prize twice this term after a string of sterling displays helped United establish themselves inside the Champions League qualification places.

De Gea joined United from Atletico Madrid in the summer of 2011 for a British record of £17.8m for a goalkeeper and after taking time to adapt to the rigours of English football has developed into the best 'keeper in the Premier League.

However, only 18 months remain on de Gea's contract and van Gaal has previously refused to answer questions regarding talks over a new deal for the Spanish international, leading to fears over his future.

Since joining United, de Gea has continually been linked with a move to Real Madrid, with Iker Casillas' days as the No.1 at the Bernabeu firmly numbered, and the 20-time Premier League champions have done little to silence the rumours.

Though van Gaal has confirmed that Valdes will be United's No.2 for the time being, the future of de Gea needs clearing up in the coming weeks before the club become vulnerable to interest from Real or another of Europe's big clubs in the summer transfer window.

Van Gaal is set to face further questions over a new contract for de Gea during his press conference prior to the weekend visit of Southampton, and should the Dutch coach again be evasive over any talks regarding a fresh deal, speculation is only likely to mount over his future.