Speaking about the keeper, Aidy Boothroyd told the CT: "Keiren was in his kit and ready to appear in the team picture but was called away at the last minute for family reasons."
Westwood, whose wife is expecting their first child, will be absent from City's League Cup tie next Tuesday as he is on international duty with the Republic Of Ireland for the international challenge match with Argentina to open the new Aviva Stadium at Lansdowne Road in Dublin.