The Academy striker was stretchered off shortly before half-time in Liverpool U23s’ meeting with Manchester City on Friday night after a heavy fall.
Brewster has an initial diagnosis of ligament damage and further tests will be conducted this week to determine the full extent of his injury.
The 17-year-old has been a regular for both Neil Critchley’s table-topping side and Steven Gerrard’s squad for the UEFA Youth League this season.