Eden Hazard set up the decisive goal for Marcos Alonso as Chelsea beat Arsenal 3-2 in a frenetic London derby.
For 20 minutes Chelsea were so good it looked like it would be a rout, with goals from Pedro and Alvaro Morata their reward.
But Arsenal roared back to level through Henrikh Mkhitaryan and Alex Iwobi within five first-half minutes.
Both sides had chances to earn the Premier League points before substitute Hazard, apparently staying put for now after a summer flirtation with Real Madrid, crossed for Alonso to net the winner nine minutes from time.
The Gunners’ attempts to play out from the back against champions Manchester City were met with ridicule and there was early cause for embarrassment here – their first goal kick had to be retaken as the pass from Petr Cech to Sokratis Papastathopoulos did not leave the area.
Arsenal manager Unai Emery, speaking to BBC Sport: “It is clear the result is not good for us but the process is continuing. Today, one thing is in the first half the reaction after 2-0, and also the efficiency. We had chances to do more score in the first half, I think we need to control the second half like we want, but I think we didn’t play like the first half and our chances were less.
“The attacking moment is all the team and the defensive moment is all the team. We need to be more compact. We need a lot of work together and it is my responsibility first, to give this compact block and to give this attacking balance.
“We need to continue working for what we want, our process, today we had two midfielders one 19 and one 21 years old, we need to give them the confidence to play, but our way, our process, is to improve and give these chances to to the young players. I think today is for not happy with the result, but the next matches to prepare well.”