Definitely think McTominay needs to start given the high he'll be on. But he's a midfielder, he got all his goals bursting from midfield, and we're missing 3, maybe 4 (depending on Sabitzer) of our CM's. So I'd certainly go with him in midfield.
Tough to predict some as we don't know if anyone is returning with an injury (Sabitzer?), or how the injured players like Rashford and Varane are progressing.
Hoping that they're all available (but with alternatives included), I think I'd go with...
De Gea
AWB
Varane / Maguire
Martinez
Shaw
Fred
McTominay
Antony
Fernandes
Rashford / Sancho
Weghorst
No satisfying midfield combination without Casemiro or Eriksen, but putting Sabitzer on the bench while he was struggling with a knee injury.