Manchester United star Juan Mata has refused to discuss the recent speculation surrounding David de Gea's future, but said the goalkeeper is "happy" and "calm" at Old Trafford.

The 27-year-old Spain international came close to joining Real Madrid in the summer of 2015. However, failure to submit the relevant paperwork on time to complete the deal before the transfer deadline resulted in the deal collapsing.

De Gea then went on to sign a four-year contract with the 20-time English champions, which will run down after the end of the next season. The Champions League winners are still believed to be interested in securing the Spaniard's services, reports the Sun.

Mata stressed his compatriot is not thinking about his future, but said "nobody knows" what will happen in the transfer window.

"I'm not a fortune teller. Nobody knows. He is happy, calm, and I imagine that he will not think for a second of this but in the present," Mata told the Spanish newspaper Mundo Deportivo.

De Gea has been one of the key players for the Red Devils over the last few seasons. The former Atletico Madrid stopper has continued to impress for Jose Mourinho's side. He has kept 15 clean sheets in 27 league games, the highest in the Premier League this campaign.

The Portuguese tactician has also dismissed recent reports linking De Gea with a move away from his current employers.

Mata also heaped praise on United's January addition Alexis Sanchez. The Chilean international arrived at Old Trafford from Arsenal and as part of the deal, Henrikh Mkhitaryan moved in the opposite direction.

The former Chelsea star said he has a better understanding with Sanchez and added that the former Barcelona man has the ability to change the course of the game.

"Personally, I have a very good understanding with him and he [Sanchez] has improved the team. He is someone who has the experience of playing in the Premier League and capable of deciding a match. He did it so many times at Arsenal that now it will benefit us," the 29-year-old explained.

Juan Mata-David de Gea
Juan Mata and David de Gea's contract at Manchester United will run down in 2019 Getty