Liverpool appeared to be on course to win 4-3 when James Milner put them ahead 15 minutes from time, only for Sebastien Bassong to equalise with a superb 20-yard drive two minutes into injury time.
However, substitute Lallana – who had earlier set up Roberto Firmino to draw Liverpool level at 3-3 – had other ideas, as his perfectly controlled left-footed volley bounced into the ground and over Declan Rudd to settle an incredible game and spark delirious Liverpool celebrations.
Liverpool’s day started well as Firmino opened the scoring in the 18th minute after a crisp passing move, but their defensive frailties allowed Norwich back in.
After Dieumerci Mbokani had levelled things up after 28 minutes, Steven Naismith put the hosts ahead as he scored another debut goal against Liverpool – having also achieved the feat for Everton.
A needless foul on Naismith from Alberto Moreno allowed Wes Hoolahan to give the hosts a two-goal cushion, but Henderson, Firmino and Milner turned the game on its head.
Yet there was more drama to come, as Bassong found Simon Mignolet’s bottom-left corner with a sweet strike, before Lallana reacted quickest to some pinball in the Norwich area to snatch all three points for Jurgen Klopp’s team.