Pep Guardiola’s men, who had thumped their rivals 5-0 in the first leg, never looked like surrendering that comfortable cushion at the Etihad.
England international Fabian Delph gave the fans something to cheer about in the 57th minute when he broke the deadlock with a powerful header.
Manchester City then held on and eventually advanced 6-0 on aggregate.
Borussia Moenchengladbach also progressed as Rafael and Hazard both scored hat-tricks, en route to an emphatic 6-1 triumph in Germany.
Elsewhere, Ajax were stunned by FC Rostov and Dinamo Zagreb made it through thanks to a late goal from Soudani. (Euronews)