A tough first half meant that the U's U18s started the season with defeat at Cardiff on Saturday.
The U's found themselves five down at the break, but recovered in the second half to keep the deficit the same.
City took the lead after just nine minutes, as Dan Griffiths headed into the net.
Eight minutes later, Sam Bowen struck from distance to make it two, before Sion Spense chipped in a third to make it three midway through the half.
A fourth came just after the half hour mark, as Griffiths got his second goal, again with his head.
And the game was taken further away from the U's on 34 minutes when Isaak Davies got the fifth.
Todd Miller had a chance for the U's as his effort was saved by the City keeper George Ratcliffe, but the U's were not to break their duck in that first half.
The second half was a more even affair as the U's prevented any further goals in their opening fixture.
U's: Hallett, Michaels (Cooke), Cracknell, Steward, Kazeem, Cornish, Maughn (Kennedy), Anderson, Hasanally (Sayer), Hutchinson, Miller