#2 Attacking midfielder
Juan Mata is still decent enough to do a job for the Reds, but decent isn't good enough anymore. United need someone of world-class ability to operateas the attacking midfielder.
Andreas Pereira seems to almost let many matches pass him by and opts for the safe options on multiple occasions. The Reds need an attacking midfielder who is not afraid to play a risky forward pass and that's why they've been frenetically chasing Bruno Fernandes.
Martial needs adequate service to score goals and he's not getting that from the likes of Mata and Pereira. When Pogba returns, this could be the ideal position for him because he has everything needed to be successful in this position. Shooting, passing, dribbling and strength are all key qualities to be successful as an attacking midfielder and the Frenchman possesses them all.
However, because of his fitness concerns, someone else needs to be signed and whether it is spending big on a player like Kai Havertz, then so be it. United have struggled to unlock defences this season and this is one of the biggest reasons as to why they've encountered that problem.