Former University of Evansville star David Weir and Lee McCulloch scored for Rangers in the second half. It played the last 36 minutes with 10 men after Alan Hutton was dismissed.
With a starting lineup averaging 22 years old and only one starter as old as 25, FK Zeta put up a brave fight against Rangers.
Rangers started the same frontline that started against Chelsea in a 2-0 win on Saturday: Scotsman Kris Boyd and new French signing Jean-Claude Darcheville in attack and McCulloch on the right wing and Charlie Adam, last year's Rangers' top rookie, on the left.
July 31 in Glasgow
Rangers (Scot.) 2 FK Zeta (Montenegro) 0. Goals: Weir 54, McCulloch 73.
Rangers -- McGregor, Hutton, Cuellar, Weir, Papac, McCulloch, Hemdani, Ferguson, Adam (Novo, 46), Boyd (Broadfoot, 62), Darcheville (Sebo, 83).
FK Zeta -- S.Ivanovic, Vuckovic, Kaluderovic, Radulovic (Djurovic 78), Igumanovic, Cetkovic (Bolevic, 83), Tumbasevic, Markovic, B.Ivanovic, Korac, Stjepanovic.
Red card: Rangers -- Hutton 58.
Referee: Georgios Kasnaferis (Greece)