United have made a £12million bid for Telles - but fuming Porto would prefer to lose him for free next summer, according to reports.
The Portuguese club are refusing to be bullied from their 20m euros (£18m) asking price despite the left-back's contract being up in June.
Porto are expected to reject the bid and Correio de Manha report that the club have been left frustrated by the Red Devils' lowball offer.
Although the player only has 10 months left on his contract, Porto are apparently willing to let him go for free rather than sell him on the cheap.
Need a VPN? Or seeking to switch? Then support Tribal Football by clicking here to sign up with our official partners NordVPN. Not only will you receive the best VPN experience, but also great discounts by signing up via Tribal Football. Thanks for your support!