Hector Bellerin's stunning injury-time strike earned Arsenal a point against Chelsea in one of the most entertaining matches of the Premier League season so far.
The two sides shared an incredible 33 chances, with the heroic keeping of Gunners' Petr Cech and Blues' Thibaut Courtois ensuring only four goals were conceded.
Courtois had made exceptional stops to deny Alexis Sanchez and Alexandre Lacazette before he was finally beaten when Jack Wilshere fired high past the Belgian in the 63rd minute.
The lead only lasted four minutes, with Eden Hazard converting from the spot to level after his foot had been caught by Bellerin.
Arsenal manager labelled referee Anthony Taylor's decision to award the penalty as "farcical", adding "you could give 10 penalties like that a game."
Chelsea must have thought they had secured all three points when Marcos Alonso flicked home substitute Davide Zappacosta's low cross after 84 minutes.
But in the second minute of stoppage time, Bellerin produced an exceptional half-volley to earn the Gunners a point.
There was more drama seconds from the end when Zappacosta's shot thundered off Cech's crossbar.