A general agreement has been struck between Manchester United and Barcelona on a 65 million euro (£56 million) fee, plus add-ons, for the Netherlands midfielder Frenkie de Jong.
However, according to club sources, there are still considerable obstacles to be resolved and the agreement is not yet finalized.
However, the development is viewed favorably in terms of the transfer eventually coming to a close.
The 25-year-old is the top summer transfer target for Manchester United manager Erik ten Hag.
On Monday, Ten Hag oversaw practice for the first time with his non-international players.
The 30-year-old Danish midfielder Christian Eriksen has an offer on the table from Brentford, thus United is yet to make any signings this summer while they wait for a reaction from him.
Although they are considering other positions as well, signing De Jong is seen as a priority.