Real Madrid are set to renew their pursuit in the goalkeeper with United braced for an approach.
Jose Mourinho does not want to lose the 26-year-old, who has now been at Old Trafford for six seasons.
However, he appears to be preparing for the possibility of a move.
Back-up keeper Sergio Romero has now signed a new four-year deal to secure his future.
And it has been claimed Leicester shot-stopper Kasper Schmeichel is among those on Mourinho’s radar to potentially replace De Gea.
David De Gea is not pushing to join Real Madrid but Ander Herrera will ensure he stays at Man Utd
Mourinho could also demand a Real Madrid star as part of a deal, with Toni Kroos and Raphael Varane admired.
De Gea has not pushed for a move away from United, though, ahead of their return to Champions League action.
But should Madrid up their interest in David De Gea, fellow Spaniard and United team-mate Herrera has assured fans he will ensure no switch materialises.
"He's happy,” Herrera said on De Gea.
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I’m going to do everything I can to make sure he stays
“I know this is going to sound repetitive because I always say the same by David is one of the few keepers who wins you points.
“I’m going to do everything I can to make sure he stays.”
Herrera himself has been linked with a move to La Liga as Barcelona are keen.
But the midfielder is now on the verge of getting a new deal at Manchester United and confirmed he is not going anywhere.
He added: “I feel valued and focused here.”