Fireworks were being set off by Arsenal fans outside Emirates Stadium last night after this emphatic victory, and who could blame them.
A week ago, after defeats by Aston Villa and Bayern Munich, the Gunners' season was in danger of derailing but now it is set up for a fascinating finale.
This was a statement victory from Mikel Arteta's side as they threw down the gauntlet to their title rivals to move three points clear at the top of the Premier League.
The pressure is on Liverpool and Manchester City to respond, with Jurgen Klopp's side able to go level on points with Arsenal if they win at Everton tonight.
The title is still in City's hands, who are four points off Arsenal with two games in hand, but this result will have made them sit up and take notice ahead of their game at Brighton tomorrow.
Chelsea were poor, but Arsenal ruthlessly put them to the sword and took full advantage to record their biggest ever victory against them.
The Gunners could have easily scored more than five and the manner of this victory will fuel belief and confidence going into the north London derby at Tottenham on Sunday.
When Ben White made it 2-0 early in the second half, this game felt over as a contest — but Arsenal did not let up.
Instead, Kai Havertz scored twice and White helped himself to another with a cross-cum-shot. This title race could easily come down to goal difference, and Arsenal's is now 13 better than Liverpool's and 12 better than City's.
Arteta's side are the Premier League's top scorers and that is remarkable, given the clamour for them to sign a striker in January.
Havertz has stepped up to the plate since then and his performance here was a reminder why he must play as this team's No9.
Arteta will surely be considering keep this whole team together for the north London derby
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At Wolves last Saturday, the German was moved back to midfield, but he is a different animal when leading the line. His link-play was excellent last night and the two goals he scored were just reward for that.
Throughout Havertz's time at Chelsea a big issue was no one knew his best position and so it was fitting that against his old club the German served up a display that confirmed he should be a centre-forward.
"He was unbelievable in all departments," said Arteta. "For a No9 to score two goals the way he did, his contribution was great."
Havertz was able to shine thanks to the midfield behind him of Declan Rice, Martin Odegaard and Thomas Partey, who bossed the game. It was the first time since the Community Shield in August that Arteta had been able to start the trio together in midfield, with injuries hampering Partey all season.
Watching this performance, there will surely be a sense of regret at that. Partey was excellent at the base of midfield, breaking up play and opening up Chelsea with his passing from deep.
It gave Odegaard and Rice the freedom to push forward, with both players excellent. Odegaard was on another level. He finished the game with two assists, but it could easily have been five or six.
Arteta will be tempted to stick with this midfield for Arsenal's final four games, starting at Spurs. That trio feels like an incredible weapon for the Gunners to unleash so late in the season. Arteta has spoken about a desire to be "unpredictable" and he may finally have his wish at just the right time.
"We thought it was a really good game for Thomas to come back," said Arteta. "He looks like he's in rhythm, he trained really well in the past few days. He had a great performance."
Never mind the midfield, Arteta will surely be considering keep this whole team together for the north London derby. Takehiro Tomiyasu came in and was assured at left-back, giving Arsenal the solidity they have been craving there. Against a Tottenham team who like to play on the counter, it feels an easy call to keep him in the side.
Tottenham should be full of running for Sunday's game, as it will be their first match in 15 days. Arsenal will have played four times in that time, but it feels like that could be an advantage. After looking dead on their feet a week ago, they have found another gear.
"What these boys have done in the last 10 days is unbelievable," said Arteta. "You look at the numbers of some of them, it's unreal. But they can do it, they can improve, because they want to, and they have this mentality that they really want to win it."