The Frenchman has agreed personal terms with the Blues over a winter transfer but Lyon are yet to sanction a deal.
An opening offer has been rejected and it is reported that the Blues may need to pay around €35 million to prise him away.
Amidst this, RMC Sport reveal that United have entered the pursuit of the 19-year-old, having watching him closely this term.
They are yet to make an approach to Les Gones but have told the player to stay patient as they prepare a formal offer for him.
United may need to offload Aaron Wan -Bissaka on a permanent deal first before stepping up their interest in Gusto.
Chelsea are currently in the driving seat to pursue him and should fancy their chances of landing him before United.
Gusto will enter the last year of his deal this summer. Lyon are bound to sell him now. His value could drop at the end of the season.