United still believe there is a chance of signing Sancho before the transfer deadline, a feeling shared by the 20-year-old's representatives.
But with a gap in valuation still to be bridged, United are interested in a short-term deal for Dembele -- who cost £135 million from Borussia Dortmund in 2017 -- to ensure manager Ole Gunnar Solskjaer gets the winger he asked for at the start of the summer.
Sources have told ESPN that United are yet to make formal contact with Barcelona, but there is a feeling an agreement may be possible because the Spanish giants are keen to raise money to fund a bid for Lyon's Memphis Depay.
Juventus' Douglas Costa, Inter Milan's Ivan Perisic and Watford's Ismaila Sarr are also under consideration as alternatives to Sancho. On Tuesday, Sancho was omitted from Borussia Dortmund's squad for their Super Clash with Bayern Munich because of respiratory problems.
United remain unwilling to meet Dortmund's €120m valuation of the England winger during the financial uncertainty of the coronavirus pandemic.
Dortmund, meanwhile, insist Sancho will stay for at least another year because their deadline of Aug.10 has now passed, although that message has not been communicated to United.
And sources also said talks with Porto about left-back Alex Telles are ongoing.