The Red Devils have been frustrated in the transfer market so far this summer, as although they have managed to sign Donny van de Beek from Ajax, Ole Gunnar Solskjaer's primary target remains Jadon Sancho of Dortmund.
Other wingers reportedly piquing United's interest are Ivan Perisic, Ousmane Dembele, and Ansu Fati, but the Barcelona pair especially are considered outlandish targets at the moment due to the coronavirus pandemic.
Even though Telles' contract expires next summer, Porto still want his release clause to be paid and have reportedly told Man Utd that they are unlikely to go much lower, despite the Premier League side initially offering around £17m for the Brazilian.
The Telegraph reports that both parties are at a stalemate of sorts over the asking price.
Telles has already agreed personal terms on the move with wages of £75,000 per week.
However, United run the risk of losing out on the Porto star as Paris Saint-Germain have now made their interest known after the knee injury suffered by left-back Juan Bernat.
They have already been usurped to the signing of Real Madrid left-back Sergio Reguilon by Tottenham after refusing to include a buy-back clause in the deal.