Dortmund sporting director Michael Zorc bullishly claimed on Monday that Sancho will play for the Bundesliga side this season and the decision was final.
And Dortmund's belief that they can retain the England star has been strengthened by developments during the process which have left them questioning how much United want to land the 20 year-old winger.
Ole Gunnar Solskjaer made Sancho his No 1 target but could now miss out on him altogether
England international Sancho is currently on a pre-season tour with Dortmund in Austria
While there was direct contact between the clubs pre-Covid that has now dried up.
And though the Old Trafford giants claimed they were worried about the slow progress of talks Dortmund have yet to receive a bid or even an indication of United's starting point for the fee negotiations, delaying attempts to find a compromise.
Dortmund have been firm from the outset in their demand for a fee of £108m.
United's finger pointing at the players' camp and claims about wage demands raised eyebrows in Germany, given the need to persuade them about a move to Old Trafford, while suggestions they have insisted on the involvement of agent Marco Lichtsteiner in the deal have been rebuffed too.
Meanwhile, United's contract offers have also caused real surprise and created further doubt about the deal at Dortmund.
Sportsmail understands United's first contract proposal would have involved Sancho taking a wage cut and their second was similar to the deal he is currently on worth up to £190,000-per-week.
United have complained about Sancho's wage demands and initially offered him a pay cut
Dortmund want £108m for the 20-year-old forward but it's not clear if United will pay that
Last week there was optimism that an agreement on terms and a five-year deal was close and that the discussions over the transfer were heading in the right direction.
Talks to sort out the personal terms element of the deal remain ongoing, with Sancho not seeking a deal that would break United's wage structure, though the fee remains the major sticking point.
United believe Dortmund's valuation is unrealistic, especially in the wake of the coronavirus crisis, and are refusing to be pushed into doing a deal on another club's