Turkish international star Arda Turan started his second consecutive game for Barcelona but was unable to have much of an effect on the scoreline despite a decent display.
Liverpool welcomed back Germany intentional of Turkish origin Emre Can who played the first 45 minutes after returning to team training from an extended break last week.
Mane opened the scoring on 15 minutes for the Reds in what was his first goal since his £30 million move from Southampton.
It was former Liverpool star Mascherano who scored an own goal. Origi then extended the lead further five minutes into the second half and then summer signing Grujic scored the fourth and final goal just before the final whistle.
Liverpool 4-0 Barcelona
Liverpool – Mignolet, Clyne, Lovren, Klavan, Milner (c), Wijnaldum (Grujic), Can (Stewart 46), Lallana (Henderson 46), Coutinho (Origi 46), Firmino (Markovic), Mane (Ings)
Unused Subs – Manninger, Moreno, Brannagan, Matip, Wisdom, Randall, Alexander-Arnold.
Barcelona – Ter Stegen (Bravo 46), Busquets (Iniesta), Denis Turan,Suárez, Messi, Cámara, Mascherano, Munir, Aleix Vidal (Sergi Roberto 46), Mathieu
Unused Subs – Masip, Douglas, Piqué, Rakitic, Mujica, Samper, Digne, S. Roberto, Alfaro, Vermaelen
Goals – Mane (15), Mascherano OG (46), Origi (50), Grujic (90)