Kirsty Wigglesworth/Associated Press
Chelsea left the celebrations for Arsene Wenger's 1,000th game in charge of Arsenal in tatters with a devastating six-goal blitz of the Gunners.
But the Stamford Bridge demolition of Arsenal's Premier League title hopes will not be making the headlines, after referee Andre Marriner was at the centre of one of the most bizarre decisions in football history.
Samuel Eto'o had begun the rout in the fifth minute before Andre Schurrle added a second two minutes later.
However, the 15th minute of the match produced the real moment of controversy.
Chelsea midfielder Eden Hazard attempted to curl the ball home from just inside the Arsenal area, but Alex Oxlade-Chamberlain dived to his left to push the effort away from any potential danger. A decision on the spot-kick appeared to take longer than expected until Marriner pointed to the penalty spot.
The match official then brandished a red card at Kieran Gibbs and not Oxlade-Chamberlain. The England international appeared to admit his guilt to the referee, but the Gunners defender did not return to the field.
Hazard slotted home the penalty, leaving the 10 men of Arsenal with an even greater uphill struggle.
Three minutes before the interval, Oscar grabbed another for the league leaders before adding a second midway through the second period.
Chelsea substitute Mohamed Salah wrapped up the scoring in the 71st minute, but the game had long since been over.
The win took the Blues seven points clear at the top of the table, albeit for just a few hours, but Arsenal's lingering title hopes appeared to have been ended by the defeat.
Chelsea manager Jose Mourinho was quoted as saying on the official Premier League Twitter feed @premierleague: "I think the game was over at 2-0 after 7 minutes. We started superbly and by the time of the penalty it was done."
Blues captain John Terry added on @premierleague: "After the early goal we were in control. The lads were pumped... All we can do is keep winning."
The Gunners must now lift themselves for the league visit of Swansea City, while Chelsea have a week off until their trip across London to Crystal Palace next weekend.
On target: 11-5