On Sunday, Arsenal didn't realise that they had broken a Premier League rule in their 2-2 draw against Manchester City.
Centre back Laurent Koscielny wore the captain's armband at the start of the match but had to be withdrawn due to injury at half time.
As it turned out, a designated stand-in captain with an armband did not seem to be in place for the remainder of the fixture which is in breach of regulations although Arsenal are unlikely to be punished.
Manager Arsene Wenger, speaking afterwards, did not seem aware or overly perturbed by the issue.
The official club captain at Arsenal is defender Per Mertesacker who has spent most of this season on the sidelines since replacing Mikel Arteta.
Elsewhere of course, we know the official captains of Liverpool (Jordan Henderson), Tottenham (Hugo Lloris), Manchester United (Wayne Rooney), Leicester City (Wes Morgan), Chelsea (John Terry), Manchester City (Vincent Kompany), Everton (Phil Jagielka) and West Ham (Mark Noble).
But do you know who the captains of the clubs below are?
