Reports have suggested that following the signing of James Rodriguez for a reported £70m earlier this summer, Di Maria had been deemed surplus to requirements at the Bernabeu, which is said to have alerted Manchester United.
He came off the bench during last night's Spanish Super Cup between the Madrid rivals, which ended in a 1-1 draw, and featured in the move that resulted in Real's goal.
"The game changed with Di Maria. It's logical [because] he's the best player they have. He's the player most likely to create openings in the opposition half," said the Atletico boss.
Paris Saint-Germain are also said to be interested in signing the 26-year-old winger.