Manchester United's bid for Sporting Lisbon star Bruno Fernandes is being held up by a gulf in valuation between the two clubs.
Sporting want £70million for attacking midfielder Fernandes, but United are unwilling to pay that figure and will walk away from any deal this month if a compromise cannot be reached.
United are understood to have bid £50m for the 25-year-old Portugal international, but consider Sporting's valuation of Fernandes to be wholly unrealistic and are not prepared to meet it.
Although United are keen to get the deal for Fernandes done in this month's window, they feel paying over the odds for him will have a knock-on effect for them with regard to future transfers.
Tottenham bid £40m for Fernandes last summer and United consider their own bid for the player - who has scored 13 goals in 21 games this season - is a fair and realistic fee, given his progress since then.
United feel if they give in to Sporting's valuation of Fernandes, that will set a precedent for future players they try to sign, with selling clubs inflating their prices as a result.
Fernandes played in what may well be his final game for Sporting on Friday night.
The Portugal international was named in the starting XI to take on Lisbon rivals Benfica, but was unable to help his side to victory.
Benfica ran out 2-0 winners thanks to two late goals from Rafa Silva.
