Man Utd reach agreement to sign Bruno Fernandes
Sporting had been holding out for €80m, with United only willing to offer an initial €50m, with a further €10.5m in add-ons.
United could pay up to €80m (£68m/$88m) for the Portugal international with several additional clauses having been agreed between the two parties despite initial €55 million (£47m/$60m).
If all goes as planned, Fernandes could make his United debut against Wolverhampton Wanderers at Old Trafford on Saturday barring any unforeseen complications.
He is due to sign a four and a half year contract to June 2024, which will include the option of another 12 months.