Manchester United are refusing to stump up Porto's asking price over Alex Telles.
It means that a transfer is unlikely to go ahead before the deadline passes next week on Monday.
The left-back's contract expires next summer and rather than pay now, United are more likely to wait until January where they can sign him to a pre-contract agreement.
The Red Devils submitted a £12m bid for the Brazilian earlier in the transfer window.
Porto rejected that offer, insisting that they wanted nearly double that at £22.7m (€25m).
United have no interest in going that high and are prepared to wait out a deal until the price either comes down or he is picked up for nothing at the end of his contract.
According to transfer guru Fabrizio Romano, Telles is desperate to move to Old Trafford and personal terms are not a problem.
But United's stubbornness in the transfer window could cost Ole Gunnar Solskjaer getting his man in early.
It has already been a slow summer in Manchester after just one arrival in the shape of Donny van de Beek.
They have also spent months trying to prise Jadon Sancho away from Borussia Dortmund, who have told them they are not negotiating.
Instead, the German club have told United to pay up the £109m asking price or walk away.
Telles was thought to be on the brink of being complete only for the Red Devils' to submit a lowball offer.
United have another option should they fail to land the 27-year-old, believed to be Dynamo Kyiv star Vitaliy Mykolenko.
Porto also do not agree with the type of offer, which included several add-ons.
Instead, they insist that they want an upfront fee - which is how they have negotiated deals in the past.
Paris St-Germain have been linked with Telles in the past but they could now look elsewhere, while Ajax star Nicolas Tagliafico is now closer to Manchester City than the red half.