I'm assuming we'll have to play a similar side that started against Wolves, with de Gea back in and probably Andreas or Lingard over Mata at the start. I think Ole will want the higher energy and pressing that these two can apply more-so than Mata, but if we can stay in the game, Mata could definitely make the difference in the last 20-25 minutes if he can keep up the level from his last two performances. He must be feeling good and confident now, but I'm not sure he'd be the right selection from the start to deal with Liverpool's style of play. Martial should also play down the middle and James in what is his supposed preferred position of left wing if Rashford can't play.
I never expect us to get drubbed even if we play badly, it's only really happened once against Everton which was an awful, awful day. Other than that, even if we're garbage we concede three at most and usually make enough chances to pinch a goal ourselves. I'll go out on a limb and say this won't be embarrassing even if we're poor on the day. However, to be fully confident of a result I'd have wanted McTominay, Pogba, and Rashford fit really. Can't be making excuses, but they'd probably still be three of the first names on the team sheet for us so it's a big ask, especially given Liverpool's form overall, nevermind at home where they seem indestructible right now.