A Djamel Delmadi goal just before the half-hour mark and a Shaun Goater effort on the hour condemned Keith Bertschin's side to their second successive Barclaycard Premiership Reserves defeat.
Blues threatened on a couple of occasions but Carlo Nash in the City goal was equal to second half efforts - tipping over the bar a Tony Capaldi shot from the edge of the box and then saving well from a Martin Grainger free kick.
On a brighter note for Blues, defender Darren Purse came through 45 minutes of the game seemingly unscathed in his first match action since an ankle injury sustained in the away victory at Fulham last December.
Blues: Marriott, Coly, Michael Johnson, Grainger, Vickers, Purse, Swierczewski, Luntala, Kirovski, Barrowman, Carter. Subs: Davies, Allsopp, Capaldi, Grondin, Martin.
Man City: Nash, Flood, Jordan, Bischoff, Dunne, Howey, Barton, Belmadi, Macken, Goater, Matias Vuoso. Subs: McCarthy, Ellegaard, Paisley, Whelan, Browne.
Reserves Results