De Gea's old deal expires today, officially making the Spaniard, who has interest from Saudi Arabia, a free agent.
United have held initial talks with Inter Milan over Andre Onana but will have to sell to finance moves for a new No.1 and a striker after committing to paying Chelsea £55m plus add-ons for Mason Mount.
The Red Devils are open to offers for a number of stars including Fred, Harry Maguire and Scott McTominay.
De Gea initially agreed terms on a new contract which would have seen him take a big pay cut but the deal was never signed off by the United hierarchy.
Champions League finalist Onana is understood to be open to a move to Old Trafford having played under manager Erik ten Hag at Ajax.
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The uncertainty over De Gea has seen United block Tom Heaton from joining Premier League new-boys Luton, who are now advancing their interest in Asmir Begovic.
England midfielder Mount will undergo a medical next week before signing a five-year-contract.