The youngster was close to agreeing a switch to Bramall Lane on in the last window, before the deal broke down when his representatives moved the goalposts on deadline day.
A Blades source told The Star that Collado’s representatives made “unrealistic demands” of the Blades to get the deal done, leaving Slavisa Jokanović disappointed in his bid to sign some wingers and reprofile his Blades squad.
United left the door open for another move for Collado in January, albeit privately acknowledging his representatives’ conduct and the fact that their situation may have changed by the time the window reopens, and the youngster was not registered with La Liga, meaning he is unable to feature for Barcelona.
If the Blades do revisit their previous interest, they will likely face competition from a number of clubs for the 22-year-old – reportedly including FC Andorra, who are 90 per cent owned by his Barcelona teammate Gerard Piqué.
Reports in Spain suggest that Real Betis and Almería have also expressed an interest in taking Collado on loan, while Parma and FC Copenhagen have also been linked. Collado is thought to favour a loan move without an option to buy, as he looks to establish himself at the Camp Nou.
Collado is under contract at Barca until the summer of 2023, but is out of favour under boss Ronald Koeman. “Collado knows his situation perfectly,” he said earlier this year. “He has to find something to play with.”