Chelsea held on for a 1-1 draw against Premier League leaders Arsenal despite Moises Caicedo's first-half red card in a fiery London derby at Stamford Bridge.
Caicedo had a yellow card upgraded to a red following a VAR check for a studs-up challenge on Mikel Merino as he became the fourth Chelsea player to be sent off this season.
Despite being reduced to 10 men, Enzo Maresca's side went in front straight after half-time when Trevoh Chalobah flicked a Reece James corner beyond David Raya with a near-post header.
Arsenal found a leveller when Bukayo Saka twisted and turned on the right-hand side of the Chelsea box and dug out a cross for makeshift striker Merino to head into the corner.
At that point, with half an hour still to play against 10 men, it seemed Arsenal were well-placed to go on and win the game but they struggled to carve out clear chances.
They went closest to a winner through Merino, who drew a sharp save from Robert Sanchez from the edge of the box, but that was one of only eight shots to Chelsea's 11 as the hosts defended resolutely.
The Gunners were without both first-choice centre-backs William Saliba and Gabriel Magalhaes for only the second time in 162 league matches and risked going down to 10 men themselves, receiving six bookings, including four in the stormy first period.
Chelsea were aggrieved that Arsenal defender Piero Hincapie was only yellow carded for an elbow which left Chalobah with a bruised cheek.
Chelsea continued to pour forward on the break in the latter stages, with substitute Liam Delap forcing a save from Raya, but the home fans celebrated the hard-earned point at the final whistle, albeit ruing what might have been had Caicedo not been sent off.
The draw means Arsenal's lead at the top of the Premier League is cut from six to five points, with Manchester City having moved above Chelsea into second thanks to their win over Leeds on Saturday.
It was clear from early in the game that Caicedo was fired up. There was a shove on Merino after he prevented a quick free-kick. He was fortunate not to be punished for a shoulder barge into the back of Jurrien Timber not long afterwards.
Caicedo was on the edge, perhaps with his hotly anticipated midfield battle against Declan Rice in mind, but Chelsea needed cool heads. His overenthusiasm spilled into downright recklessness when he went studs up into Merino's ankle for his red card.
The sending-off left Chelsea in a familiar position. At least they had got some practice in playing with 10 men. But they were the better side before it. A battling point draw might have been a win had it not been for Caicedo's rush of blood to the head.
The ill-discipline undermined them. And not for the first time this season. Maresca needs to eradicate the issue quickly.
Chelsea boss Enzo Maresca to SportNews: "I think we showed we are heading in the right direction.
"I always say the same. The performance has been fantastic.
"We were a much better team than them 11 vs 11 but with 10 players, it is difficult but we dealt with it outstandingly.
"11 vs 11, we were better than them.
"We tried to exploit the best solution, the best space. We knew the space was for Malo [Gusto] and Estevao on that side. Tonight we can be happy even if we didn't win.
Arsenal boss Mikel Arteta said in his press conference: "I think it was a really proper London derby. Really intense.
"You could sense from the beginning that every duel, every action had something on it.
"Two teams very willing to win and not much football. It was a lot of restarts, a lot of free-kicks, a lot of yellow cards, so not a lot of fluidity.
"We managed to get some good spells without having too much momentum. We scored a great goal. And after that, we had two or three big chances, but we lacked certain details."
On the extent of the injury that ruled out William Saliba, he added: "I don't know. I think he's got another test tomorrow. We'll need to see the extent of that feeling, that sensation that he had and we'll know more."
Arsenal's Mikel Merino told SportNews of Moises Caicedo's red-card tackle: "I felt my ankle go all the way.
"Luckily, I have very mobile ankles and body so I wasn't concerned about myself.
"But I knew it was a horrible challenge and a red card straight away."
He added: "On one hand, disappointed because we didn't win. When you wear this shirt, you want to win every game.
"But on the other hand, this is going to be a long season. It's a really tough stadium to come to. We'll take the point."
Chelsea captain Reece James to SportNews: "It's disappointing to come away with only one point.
"We went down to 10 men pretty early and that made it difficult. We had a lot more of the ball when it was 11 vs 11.
"Everyone can see where we are and what we're fighting for. Today was a big statement, even though we wanted to win, there's positives to take from that."
