The midfielder said he didn't know of any Real Madrid interest in his Spanish teammate at Manchester United.
Speaking to the International Business Times, the attacking midfielder didn't claim to know of any interest his former team had in De Gea, before openly admitting that he would personally wish for the Spanish stopper to remain in the North West of England.
Mata urged the press to ask the 24-year-old about whether the La Liga giants were looking to sign him, insisting he had no knowledge of any concrete interest: "I don't know. To be honest, I don't know," he told the IBT. "Ask him [De Gea] because I don't know."
Whether Mata knows for certain or not, he will certainly be aware of the rumours surrounding De Gea, and those rumours will not have gone away after Iker Casillas could be counted as somewhat responsible for the goal that saw Real knocked out of the Champions League on Wednesday night.
What the World Cup winner was sure of was his compatriot's importance to Louis van Gaal's side, with the former Atletico goalkeeper a vital figure in United's 2-1 win over Crystal Palace at the weekend.
"I understand how importance he is for us", Mata added.
"Against Crystal Palace he proved it again with a save that gave us the three points. I wish him to stay. Being selfish, I obviously hopes him to remain with us. He gives us many points..."
And if he asks around the training ground, Mata may find that there are plenty more that are keeping their fingers crossed that the Premier League's best goalkeeper will be at Old Trafford next season.