With neighbours Man City continuing to deliver outstanding performances, the gap between the two clubs has widened to eight points after 11 Premier League games.
Paul Pogba's long-term injury hasn't helped Man Utd's cause, while Henrikh Mkhitaryan has suffered a drop in form and Romelu Lukaku has endured a seven-game goal drought.
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Jose Mourinho is probably still unsure as to what his best XI is, and the position which seems to be most up for grabs at Man United is left-back.
With that said, a rising South American defender, relatively unknown to many people, has now confirmed that United are interested in signing him.
Argentine star says Man Utd want him
Man United have been closely monitoring a young left-back, who can also play as a central defender, and his name is Enzo Diaz.
The promising full-back plays for second tier club Agropecuario in his homeland of Argentina and has not only claimed that Man Utd want to sign him, but that a move would be his "dream".
"I found out about it (Man United's interest) on Saturday morning," Diaz told Ataque Futbolero, via Goal. "But later, I did not talk to anyone other than my agent."
The 21-year-old continued: "My agent told me that they were delighted and they were going to see me in a couple more games.
"It is the dream of any footballer (to play for Manchester United). However, I need to remain focused on what we are doing and enjoying this moment."
Given that Diaz has only made six league appearances for Agropecuario, he is right to stay calm, focused, and ensure that he continues to improve as a footballer.
On the other hand, the inexperienced Argentine must be a bright prospect if one of the world's biggest clubs is tracking him after a handful of first-team matches since breaking through.
Do Man Utd need a left-back?
As mentioned above, Mourinho already has several options in the left-back position, but none of those players have been able to nail down the spot.
Luke Shaw, Daley Blind and Matteo Darmian have all been used in the role, with former winger Ashley Young currently getting a run in the team as a wing-back.
Do YOU think Diaz would be a good signing for Man Utd? Be sure to leave YOUR opinion in the comments box below!