The 19-year-old has been out of action for over a year with a knee injury but was widely tipped to make his debut for the senior side this campaign.
Brewster is yet to make his a competitive appearance for Liverpool but Jurgen Klopp is a huge fan of the youngster's abilities and has tipped him to be the next huge star from Liverpool's youth sides.
Speaking about his inclusion in the squad, Klopp said: "He is the next really exciting prospect.
"If you see him training… next season will be his season, his first real season.
"He is now physically an adult, he grew a lot, he worked a lot and the training session today was, to be honest, pretty impressive.
"He is with us, he is our player and we want to have him around. In this case I thought, ‘Come on, it's Barcelona, let's give him a first sniff.'"