In Arsenal's 6-0 defeat at Chelsea, referee Andre Marriner was embarrassed when he sent off Kieran Gibbs for a deliberate handball in the penalty area that was clearly the work of Arsenal team-mate Alex Oxlade-Chamberlain.
If you feel confident that you can tell Kieran Gibbs and Alex-Oxlade Chamberlain apart, you simply answer picture-based questions to identify one from the other.
On the website, most images tend to feature one player's squad number on the back—which does make things simpler.
Of course, in the event that you get one wrong, you are sternly ticked off:
It remains to be seen what punishment will be issued to Marriner himself for the mistake.