twelfth man

English Wikipedia has an article on:

12th man (football)

Wikipedia

• Audio (General Australian):

  (file)

twelfth man (plural twelfth men)

1. (cricket, rare in the plural) A designated substitute player who may field but not bat or bowl.

   Synonym: (humorous) drinks waiter

2. (sports) Collectively, the fans of a team in many eleven-a-side sports, seen as helping the team to succeed.