Brewster, 18, was making his first appearance since January 2018 as Liverpool's youngsters took on Northwestern University.
The teenager played the first 45 minutes for the Reds and scored twice as they ran out 4-0 winners.
Brewster opened the scoring with a stunning effort from outside the area before tucking in a rebound for his second.
Reds coach Neil Critchley said: "He's been out a long time and we've missed him. It was great for him to finally get back playing in a game and to score two goals was brilliant for him.
"His first goal was a fantastic strike and then he was there to put the second one in.
"Hopefully there's no issues - and I'm led to believe there isn't - and he can build on that."