Sources close to the deal say that 25-year-old Juan Mata is now preparing himself for a medical ahead of the move
It is understood that United have now finally submitted a bid.
There were suggestions from sources close to the deal that the 25-year-old Spaniard is now preparing himself for a medical ahead of the move which would smash United's transfer record.
United face Sunderland in the second-leg of their Capital One Cup semi-final tonight, trailing 2-1, and are aware of the uplift they would receive from their supporters if they confirmed the deal prior to kick-off.
However, United manager David Moyes will rebuff suggestions that a deal is close for Mata unless it has been agreed.
It is understood that an outline agreement has been reached involving the two clubs.
As a consequence of that Mata's advisers, including his father Juan senior, have flown in from Spain in the hope of closing the deal within the next 48 hours.
Senior sources at United confirmed to Telegraph Sport today that talks were continuing to progress. The club want to remain cautious as they are mindful of the criticism they would receive if the move collapsed after failed bids last summer for Cesc Fabregas and Gareth Bale.
Discussions have reached a detailed stage and sources say that there are still "two or three" matters that need to be resolved, but they do not expect these to be insurmountable.
Mata was conspicuous by his absence at Chelsea's Cobham training ground today as the rest of the first-team squad were put through their paces by manager Jose Mourinho, who is understood to have sanctioned the move if an acceptable price - £37 million - is agreed.