Chelsea should have been celebrating their most accomplished performance of Mauricio Pochettino's reign and, arguably, since Todd Boehly bought the club, but still couldn't win.
At 2-0 up, Pochettino's side had outplayed Mikel Arteta's typically exceptional group physically, mentally, technically and tactically.
Cole Palmer scored a much-deserved 15th-minute penalty by sending David Raya the wrong way at a VAR check led to William Saliba's handball in the box being penalised.
The £45million signing from Manchester City was exceptional as a false 9 and was unlucky not to add a second minutes later after a low drive.
After a brief second half stoppage, Pochettino hugged his forward who has been transformational since joining Chelsea and almost led his team to their fourth win in his fourth start.
Mykhailo Mudryk's cross flew into Raya's net just after half-time to make it 2-0. It was a moment of luck but, having dominated the full 90 minutes, one Chelsea ultimately deserved.
From one to almost 11, Chelsea were exceptional. Marc Cucurella and Malo Gusto won their duels against Arsenal's dangerous wingers Gabriel Martinelli and Bukayo Saka.
For Cucurella, in particular, it was a huge moment as he returned to play at left-back after Chelsea spent much of this summer trying to sell him.
The midfield three have clicked ever since the 2-0 win over Fulham in early October and dominated Arsenal trio Martin Odegaard, Declan Rice and Jorginho.
The one major concern is Robert Sanchez's performance, which proved poor all evening. His errant kicking and rushing out put Chelsea under pressure and ultimately allowed Rice to pull one back from 25 yards.
Gusto switched off at the back post, allowing Leandro Trossard to equalise and complete a late collapse.
Reece James played out the last 10 minutes of the match in a welcome return after over two months out injured.
Pochettino's substitutions may also be questioned with the team declining after he, Nicolas Jackson and Noni Madueke came on.
Even still, Chelsea's confusing transfer activity and chaotic squad-building exercise is beginning to make some sense.
They have begun to look like a Pochettino with Tottenham needing until November to come good and Paris Saint-Germain needing half a season.
Chelsea look the high-level and competitive team that they need to be to beat teams like Arsenal, which is crucial given they face Tottenham, Manchester City, Newcastle and Manchester United in the coming weeks.
