Christian Eriksen made his Red Devils debut in a false-nine role that failed to spark the team against Brighton as Erik ten Hag missed his first game in charge.
If Ronaldo started today, then Eriksen will return to midfield against his former employers to force one of Fred or Scott McTominay out of the starting XI.
Marcus Rashford also starts as transfer rumors surrounding him continue to swirl with PSG keen.
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Ten Hag have revealed that both centre-back Victor Lindelof and forward Anthony Martial are injury doubts for the game. Facundo Pellistri, Brandon Williams and Phil Jones may also miss out, meanwhile.
Manchester United starting XI (4-2-3-1): De Gea; Dalot, Maguire, Martinez, Shaw; McTominay, Eriksen; Sancho, Fernandes, Rashford; Ronaldo.