The Sunsays both Spanish giants are tracking the exciting 24-year-old as they identify their top transfer targets for the summer.
Their interest will be a major blow to United, who have made Grealish their No 1 option to become the new playmaker at Old Trafford.
Grealish's sparkling form has convinced a number of Premier League and European clubs he is the real deal.
And he has not escaped notice from Spain's top two clubs.
Now Villa are steeling themselves for offers at the end of this campaign.