Red Star Belgrade butchered a surprise chance to go ahead at Anfield, and the hosts made them pay within moments.
Roberto Firmino reaped the rewards of a fine set-up by Xherdan Shaqiri and Andy Robertson, and Liverpool opened up a 1-0 lead in their UEFA Champions League match against the Serbian powers.
[ MORE: Champions League standings ]
Shaqiri starts the play with an interceptions, then playing an inch-perfect pass into the box for Robertson.
The Liverpool left back cuts a ball toward the spot, and Firmino takes a touch before his slightly-deflected shot wrong foots Canadian keeper Milan Borjan to put the Reds on top.
A win guarantees Liverpool a spot in Group C’s Top Two at the midpoint of the group stage.