An outstanding first-half performance by Arsenal saw them beat London rivals Chelsea 3-0 at the Emirates and go third in the Premier League table.
The Gunners delivered an early sign of intent when Alexis Sanchez saw an early 20-yard strike stopped by Thibaut Courtois.
And they were 2-0 up after 14 minutes as Chelsea's defence suffered a nightmare afternoon.
With 12 minutes played, Gary Cahill dawdled on the ball before making a mess of his backpass and allowing Sanchez to race through and chip coolly beyond Courtois.
Two minutes later, the Gunners doubled their lead with a superbly-worked goal as Mesut Ozil and Alex Iwobi set up Hector Bellerin to cross for a Theo Walcott tap-in.
A shell-shocked Chelsea offered little in response apart from a low Willian effort that whistled just wide of the far post and were three goals adrift with five minutes of the first half still to play.
The goal began on the edge of the Arsenal penalty area as Ozil turned past a couple of challenges and raced into the Arsenal half before finding Sanchez.
The forward then chipped the ball over Cahill and David Luiz, who had both been drawn towards him, and Ozil volleyed into the ground, over Courtois and off the post, to make it 3-0.
Diego Costa -- booed by the home fans having been involved in controversial incidents against Arsenal in the past -- tried to drag his team back into the contest with a couple of strong runs at the start of the second half.
But it was the Gunners who continued to have the chances, with Walcott crossing too high for Sanchez and the Chilean then failing to find Ozil with a low ball to the far post.
Courtois blocked a Walcott drive and Granit Xhaka, a first-half substitute for the injured Francis Coquelin, lashed over the bar as Arsenal again threatened to score a fourth.
Chelsea, who slip to eighth after a second successive Premier League defeat, mustered only two efforts on target on what was a dismal afternoon for new boss Conte.