Offrande Zanzala scored the decisive goal and was later sent off as Derby County claimed a 1-0 victory at Birmingham City in their opening Premier League Cup Group A contest.
Zanzala scored from close range five minutes into the second half before receiving a late red card at the Birmingham County FA Headquarters in Great Barr.
Derby's next Group A match is against Nottingham Forest on 6 November, while Birmingham travel to Middlesbrough on the same day.