Mourinho was desperate to add winger Ivan Perisic to his squad, but Inter Milan played hard ball with the Croatian, who eventually signed a new contract keeping him in Milan until 2022.
The Portuguese made it clear he wanted to sign four players in the transfer window at the beginning of the season, but only managed to secure three signatures.
The Red Devils have been linked with Spanish global and Valencia star Carlos Soler for quite some time and according to Independent, Mourinho has made the 20-year-old his top transfer target in January.
The Valencia winger is said to have caught Mourinho's eye after he missed out on other attacking targets in the summer. His club appear to have benefited from his displays, as they are now second in the table - four points ahead of the two Madrid giants, and four behind first-placed Barcelona.
Mourinho is committed to United for now.
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Soler, 20, only made his first-team debut just under a year ago but has been integral to Valencia's success, making 11 appearances - scoring once and registering four assists.
With a pivotal month ahead for United with trips to Watford, Arsenal and the visit of the Citizens - as well as the upcoming festive schedule - Pogba's return will give Mourinho and the Red Devils' fans hope of a resurgence in form.
Though fortunes on the pitch have improved dramatically on the pitch for Valencia this term, following two consecutive 12th placed finishes, they are still not in a healthy position financially.
But, failure to do so would require them to raise the cash elsewhere and that is why Soler maybe sold.