Maksym Talovierov had given the EFL Championship struggler a shock lead in the first half, but a relentless wave of pressure eventually told as City advanced to the quarter-finals.

As expected, City dominated the opening stages, with Ilkay Gundogan's header from Bernardo Silva's inch-perfect delivery brilliantly saved by Conor Hazard from close range.

Gundogan was again involved for the hosts moments later, striking the post with a left-footed effort. But the 8,000 travelling Argyle supporters were sent into raptures in the 38th minute.

From its first corner of the contest, Talovierov rose highest to glance Matthew Sorinola's set-piece beyond the grasp of Stefan Ortega as the Championship struggler looked to write another page in the competition's historic storybook.

City continued to probe for a leveller, with Vitor Reis heading narrowly wide from close range before Hazard got his fingertips to Kevin De Bruyne's low drive, but the visiting goalkeeper would have hoped to do better for the hosts' equaliser.

O'Reilly nodded De Bruyne's free-kick into the bottom-left corner with the aid of a touch from Hazard on the stroke of half-time, with Pep Guardiola's side knocking on the door for the remainder of the contest.

It completed the turnaround when Phil Foden's set-piece was met by a towering header from O'Reilly, before De Bruyne sealed City's progression to the final eight in the 90th minute after being teed up by Erling Haaland inside the box.