Have Cardiff City ever had a smaller crowd against top-flight opposition in any competition than the 6,013 attendance against Brighton & Hove Albion? Not a rhetorical question, I honestly don't know the answer. However, I'd be very surprised if any competitive game against a team from the top division has ever attracted a smaller home crowd.

Some other EFL Cup crowds this evening:

20.090 - Norwich City v Bournemouth
10,769 - Nottingham, Forest v Wolves
10,459 - Huddersfield v Everton
7,973 - Sheffield Utd v Derby County
7,491 - Swansea City v Plymouth
6,193 - Stoke City v Doncaster