Kieran Gibbs was the victim of mistaken identity as he was sent off for a foul he did not commit.
With Arsenal struggling, down 2-0 in just the 15th minute, Alex Oxlade Chamberlain dived a full stretch to stop a goal bound Eden Hazard shot.
Confusion surrounded afterwards as referee Andre Marriner identified Kieran Gibbs as the culprit and issued him with the red card. Chamberlain appeared to tell the referee that it was him and not Gibbs that handled the ball but it was Gibbs who headed for the early shower.
To add to the Gunners pain, Hazard converted the penalty to put Chelsea 3-0 up in a game that ended 6-0 to the home side, to put a huge dent in Arsenal’s title challenge.