Chelsea are currently nine points clear at the top of the Premier League table.
Manchester United are 14 points behind Antonio Conte's side, and lie in sixth place in the table.
But De Gea insists United will keep fighting, despite the huge defect.
David De Gea admits Manchester United will keep fighting Chelsea
"The truth is that they [Chelsea] have it very well," De Gea told Spanish outlet AS.
"They are nine points above second and they have the title in their hands.
"We are all going to fight to get as high as possible but they are very well placed.
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Jose Mourinho didn't look too excited as he was driven to Carrington
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David De Gea's Manchester United are 14 points behind Chelsea in the table
"Obviously, when you do not get to fight to win the Premier League, I do not know if you can say it is a disappointment but in a club as big as this you always have to fight it.
"It is already very difficult.
"Chelsea have it much closer but we will continue fighting until the end."