Chelsea was held to a 0-0 draw for the first time in almost 20 months on Sunday when Arsenal produced the type of disciplined display lacking during recent setbacks to frustrate the Premier League champions. Just like in the curtain-raiser to the season when Arsenal beat Chelsea in the Community Shield, the west London club finished with 10 men. David Luiz was sent off in the 87th minute for a high, sliding challenge on Sead Kolasinac.
Asked about Chelsea's fifth red card in eight matches, Chelsea manager Antonio Conte responded: "Do you think we are becoming bad?" The Italian did acknowledge: "It's a situation we need to improve."
It was the most explosive moment of a largely sedate lunchtime fixture with Arsenal transformed from the side that collapsed so meekly to lose 4-0 at Liverpool on top of a defeat to Stoke.
"I think we needed that, after Liverpool," Arsenal midfielder Aaron Ramsey said. "We showed we wanted a result today and we've got one. We have come here and struggled in recent years but we showed what we're capable of, competing against the best.
"We showed solidarity, that we can create chances against them, and on another day we might have nicked it."
Such as when Ramsey was given the freedom to exploit pockets of space and waltz unchallenged through the defence just before halftime. Only the post denied Ramsey and record-signing Alexandre Lacazette couldn't follow through with a goal.
Although the Gunners lacked time to make the most of its man advantage, they still made Chelsea settle for a goalless draw in the league for the first time since February 2016. Coming on top of the FA Cup final win over Chelsea in May and Community Shield success, Arsenal has the upper-hand in this London rivalry at the moment.
"We feel we're in a good place," Ramsey said, "and now need to keep building on this."
Arsenal goalkeeper Petr Cech was rarely troubled on his return to Stamford Bridge where he won every major honour with Chelsea over 11 years. Collecting a couple of strikes from Pedro Rodriguez in the first half and a shot from Eden Hazard in the second half was about as testing as it got for Cech.
Thibaut Courtois had to be far more alert in the Chelsea goal, particularly in the first half when Hector Bellerin's pace was unsettling the hosts on the right flank as he combined with Danny Welbeck. A fitting cross from Bellerin was headed wide by Welbeck and the striker also turned a cutback into the 'keeper.
"We had a lot of possession in the first half and tried to create but it felt frustrating," Chelsea captain Gary Cahill said. "They defended well, we couldn't open them up."