The Brazilian stopper is expected to make his debut ahead of Loris Karius as the Reds play their penultimate pre-season encounter before the Premier League begins next weekend.
Liverpool released an official statement announcing Alisson's "provisional" number, and confirmed that the goalkeeper will be assigned an official number in due course.
"[Alisson] will have 'A. Becker 13' on his shirt for the game at the Aviva Stadium but supporters should note that this is a provisional, unconfirmed squad number for the Brazil international," the statement read.
"The club will announce Alisson's permanent number in due course, and that of fellow summer signing Fabinho, who has provisionally been wearing No.3 in pre-season."
Alisson became the world's most expensive goalkeeper after joining Liverpool from Roma for £67m.