Bentley is ineligible as he has already played in the competition for his parent club, Tottenham, this season.
Out of the running: Bentley is ineligible for the Carling Cup clash
Sebastian Larsson is set to replace Bentley as City look to overturn a 2-1 first leg deficit.
Blues boss Alex McLeish has no fresh injury concerns with JamesMcFadden (knee) and Scott Dann (hamstring) long-term casualties.
Team (from): Foster, Carr, Johnson,Ridgewell, Murphy, Larsson, Ferguson, Mutch, Fahey, Hleb, Derbyshire,Taylor, Jerome, Gardner, Bowyer, Zigic, Jiranek, Phillips, Parnaby,Beausejour.
Newcastle to refuse Birmingham's £1.5m offer for striker AmeobiStoke told Jerome will cost £8m as Birmingham aim to sign Tuncay BIRMINGHAM CITY FC