Match ends, Arsenal 2, Chelsea 2.
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 him in the 63rd minute.
The lead only lasted four minutes, Eden Hazard converting from the spot to level after his foot had been caught by Bellerin.
Arsenal manager Arsene Wenger labelled Anthony Taylor's decision "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.
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Stunning strikes earn Gunners point
It was error-strewn and exhilarating end to a back-breaking festive period for both sides.
Arsenal, playing their sixth game in 19 days, just had the upper-hand in the opening exchanges.
Sanchez saw a shot come off both posts after a stunning stop from Courtois, before the Belgian pushed away a low strike from Lacazette.
The French summer signing was a constant menace to the Blues' defence. He had another low effort come off the heel of Courtois and was denied again when his turn and shot was pushed around the post.
However, it was the unlikely sources of Wilshere and Bellerin - with just two goals between them in all competitions this season at kick-off - who managed to find a way past Courtois.
Wilshere, who had not scored in the top flight since May 2015, gave the Gunners the lead when he smashed home high past the goalkeeper from eight yards.
And with the Gunners staring at defeat, Bellerin, who conceded the penalty, produced a brilliant side-foot half-volley to raise the roof at the Emirates.
Off-target Morata costs Chelsea
Chelsea had 19 of the 33 chances on goal in the match, with top-scorer Alvaro Morata wasting three one-on-one opportunities.
His first should have given Chelsea the lead, but he inexplicably slid the ball well wide. He then beat Rob Holding for pace but his dinked finish drifted over the bar.
And moments after Bellerin scored, the Spaniard was faced with another one-on-one but fired straight at Cech before Zappacosta followed up with a vicious strike that came off the bar.
Cech was brilliant and made two great low saves from Hazard and Alonso before he was beaten by the pair.
Hazard, with another effervescent display, scored the equaliser from the spot after Bellerin caught his foot with his studs.
And then wing-back Alonso scored his third goal in his last five appearance when he swept in after good work from Zappacosta on the right.
Man of the match - Eden Hazard (Chelsea)
'Morata has not had luck this period' - reaction
Chelsea manager Antonio Conte: "I think it is a pity because when you have so many chances to score you must win the game. Instead we are talking about a draw against a good team, but in this game we deserved to win as we created a lot of chances.
"We must be disappointed, we had a great chance to win, but we must accept the final result. We win together, we lose together, we draw together."
On the performance of Morata: "It is not luck in this period, he has to continue to work and continue to improve. For a striker it is very important to score. It is a pity, he had many chances to score, but I'm very happy with his commitment and effort for the team."
Arsenal manager Arsene Wenger: "It was a great football game. That's what you want people to talk about. The media and social networks drive everyone crazy today, but what is important to me is a good football game.
"We played three games in six days and you could see the team gave absolutely everything. We have a busy schedule and have made bad decisions but there is still great quality in our games."
Wilshere ends 43-game drought - stats
- Arsenal have avoided defeat against Chelsea in their two league meetings of the season (drawn two) for the first time since 2011-12.
- Chelsea manager Antonio Conte has enjoyed just one victory in his six meetings with the Gunners in all competitions since the start of last season (D3 L2).
- This game was Wenger's 60th meeting with Chelsea in all competitions - making them the side he has faced the most as Arsenal boss (W22 D17 L21).
- Wilshere scored his first goal in his last 43 Premier League games, since netting against West Brom in May 2015.
- Each of the 14 penalties Cech has faced in the Premier League with Arsenal has been scored.
- Since the start of last season, Marcos Alonso has been directly involved in 16 Premier League goals (12 goals, four assists), four more than any other defender.
- Hector Bellerin bagged his first goal in his last 22 Premier League games, since netting at the tail-end of last season against Everton.
Arsenal are at Championship club Nottingham Forest in the third round of the FA Cup on Sunday (16:00 GMT) and face Chelsea again in the Carabao Cup semi-final first leg next Wednesday (20:00 GMT). Before that match Chelsea are at Norwich's Carrow Road on Saturday (17:30 GMT) for their FA Cup tie.
- 21ChambersSubstituted forWalcottat 88'minutes
- 16HoldingBooked at 53mins
- 10WilshereBooked at 31mins
- 11ÖzilBooked at 67mins
- 9LacazetteSubstituted forWelbeckat 80'minutes
- 13CourtoisBooked at 89mins
- 15MosesSubstituted forZappacostaat 56'minutes
- 4FàbregasBooked at 43minsSubstituted forDrinkwaterat 71'minutes
- 10E HazardSubstituted forWillianat 82'minutes
- Anthony Taylor
- Shots on Target
Second Half ends, Arsenal 2, Chelsea 2.
Davide Zappacosta (Chelsea) hits the bar with a right footed shot from the centre of the box.
Attempt saved. Álvaro Morata (Chelsea) right footed shot from the centre of the box is saved in the centre of the goal. Assisted by César Azpilicueta with a through ball.
Goal! Arsenal 2, Chelsea 2. Héctor Bellerín (Arsenal) right footed shot from the centre of the box to the top left corner.
Attempt blocked. Alexis Sánchez (Arsenal) left footed shot from the centre of the box is blocked.
Rob Holding (Arsenal) wins a free kick in the defensive half.
Foul by Álvaro Morata (Chelsea).
Offside, Arsenal. Shkodran Mustafi tries a through ball, but Theo Walcott is caught offside.
Thibaut Courtois (Chelsea) is shown the yellow card.
Attempt blocked. Shkodran Mustafi (Arsenal) right footed shot from outside the box is blocked.
Substitution, Arsenal. Theo Walcott replaces Calum Chambers.
Corner, Arsenal. Conceded by Andreas Christensen.
Attempt missed. Héctor Bellerín (Arsenal) right footed shot from the right side of the box is too high.
Goal! Arsenal 1, Chelsea 2. Marcos Alonso (Chelsea) right footed shot from the centre of the box to the centre of the goal. Assisted by Davide Zappacosta with a cross.
Substitution, Chelsea. Willian replaces Eden Hazard.
Calum Chambers (Arsenal) wins a free kick in the attacking half.
Foul by Álvaro Morata (Chelsea).
Substitution, Arsenal. Danny Welbeck replaces Alexandre Lacazette.
Foul by Alexandre Lacazette (Arsenal).