Mayoral is considered to be one of Madrid’s most promising young players having scored seven goals in seven appearances in last season’s UEFA Youth League.
He also helped Spain win this summer’s European U19 Championship with three goals in five games, finishing as the competition’s top scorer.
De Gea’s potential transfer to Madrid had looked to have petered out after Sergio Ramos signed a new deal at the Bernabeu.
United were adamant that De Gea would only be sold if Ramos went the other way or a world record bid came in.
Mayoral is undoubtedly a fantastic prospect but United would be wise to bring in a proven striker rather than one who will need time.
Louis van Gaal has Wayne Rooney, Javier Hernandez and James Wilson as his only out-and-out strikers and Rooney has looked sub-par in United’s three fixtures so far. Regardless, De Gea should be made to see out the final year in his contract now that Ramos is staying.