Attack
United are leaning on the left side when it comes to attack, with most of their attackers, barring Lukaku, preferring the left position. Sanchez is the first choice down the left right now, but Rashford and Anthony Martial also fit in there fine. Both youngsters can fill in for Lukaku down the middle as well. It is on the right that most of United's problems lie.
However, in the absence of reinforcements, Mourinho might be tempted to tweak things a bit, to make United a force to reckon with. Lukaku is untouchable as the front man, the focal point in the attack. Sanchez could be shifted to the right, a position he has played at during his time at Barcelona.
This would enable Rashford to come in on the left, a move that would benefit all parties. Rashford has recently been upgraded as the new No. 10 for United and he joins a long line of fabulous players who wore the famous number. It shows the confidence his manager has in him and Rashford should be using that as an inspiration this season.
However, if Mourinho does not want to shift his charismatic no. 7 to the right, Mata or Lingard or even Rashford could do a job there as well. In any case, the strongest United attacking line up should feature Alexis Sanchez, Marcus Rashford and Romelu Lukaku.