Under-23s boss Neil Critchley will take charge of the Reds at Villa Park while Jurgen Klopp and his senior stars prepare for a Club World Cup semi-final against Monterrey in Qatar.
Liverpool has been forced to field two teams in two competitions on two continents this week due to a fixture pile-up in a manic December for the Premier League leader.
Already without Virgil van Dijk, Sadio Mane, Mohamed Salah and the rest of its established names, Liverpool might also be shorn of England youth international Brewster.
The 19 year-old, who has appeared twice in the EFL Cup this season, is dealing with an ankle issue.
"He's got a knock so he's doubtful," Critchley said. "We're assessing him today - fingers crossed he makes it. We'll see."
Should Brewster recover in time to play, he is one candidate to then join Klopp's senior group at the Club World Cup, with travel arranged for after the Villa match.
"Possibly [some players will travel]. I believe there's a flight waiting," Critchley said. "It might depend on how they play in the game.
"We shall see. I think one or two might take that journey. I might try to sneak on the plane myself."
Critchley is approaching the game with optimism, knowing little is expected of what is essentially a reserve side against a Premier League outfit.
"I don't think we can lose really," he said. "We've just got to go and give everything we've got, be there for each other from the first whistle. We always try to dominate the game but understand that's going to be extremely difficult tomorrow night.
"These players want a tough challenge, they need tough challenges. The next step in their careers is the toughest. I hope they go and prove to everyone watching what they're capable of."
The unlikely scenario has thrust Critchley and his young charges into the spotlight, but he is relishing the opportunity.
"The decision was taken above me. It was for the club to decide, and this is what they've come up with. It's a unique set of circumstances - I don't think it's ever happened before.
"We tried to find what we think is the best solution, and myself and the players who are going to be there tomorrow night are the beneficiaries of that decision.
"We're looking forward to it, we can't wait, and we're going to go and give everything we've got on the pitch from the first whistle."