Alisson Becker lasted less than 40 minutes of the new Premier League season before limping off with an injury.
The Liverpool shot-stopper slipped after taking a quick free kick and appeared to in some pain as he held his right leg.
Summer signing Adrian came on to take his place, with the former West Ham No.1 getting a warm reception from the Kop on his debut.
But the injury to Alisson will be a real concern to Jurgen Klopp, who had otherwise watched a flawless first half display from his side.
Norwich, back in the top flight after a three-year absence, gifted the European champions a seventh-minute lead via Grant Hanley’s own goal and quickly crumbled as Mohamed Salah, Virgil Van Dijk and Divock Origi added to the score before half-time.
The Canaries looked much better in the second half as Teemu Pukki pulled a goal back but there was nothing they could do to prevent a 10th straight Premier League win for the hosts.
However, what could have been the perfect start to what Liverpool hope will be another title challenge had the sheen taken off by Alisson’s injury as the Brazilian went down clutching his calf after slipping while playing a goal kick.
It did nothing to slow Liverpool on the night, however, as Origi added a fourth three minutes before the break, heading home a sumptuous cross from Trent Alexander-Arnold.
Adrian had not had a save to make since coming on but in the 64th minute he was picking the ball out of the net after Emiliano Buendia slipped in Teemu Pukki and he calmly slotted the ball home as the visitors grabbed a consolation.
12.30pm, 3pm and 5.30pm – delivering award-winning coverage to more GameDay listeners than ever.