Arsene Wenger reaches 20 years as Arsenal manager next week and during that time he will not have enjoyed many victories more than the beating his side doled out to Chelsea at the Emirates Stadium on Saturday evening.
The 66-year-old saw the Gunners completely overrun their London rivals and they fully deserved the 3-0 win that lifts them to third in the Premier League.
Alexis Sanchez got the ball rolling as he marked his 100th Arsenal appearance with the opening goal, stealing in to rob Gary Cahill of possession before finishing well as Theo Walcott and Mesut Ozil also struck in a fine first-half for the hosts.
Arsenal may face Basle here in a Champions League game on Wednesday but, on the week of his landmark anniversary, this was the game Wenger would have been desperate to win.
He reaches his milestone on 1 October and, despite being in charge for two decades, the Frenchman had not tasted a Premier League victory over Chelsea in nearly a quarter of that time.
Speaking after the game, the Frenchman told BT Sport: "I am very happy because we needed to change the recent history, I thought we did it with style and steel and that's what we wanted. I think we were committed with discipline.
"We lost (Francis) Coquelin - and Granit Xhaka came on and straight away he was at the level of the game and that makes a big difference.
"We want to play with technical qualities and pace and I hope that this kind of performance convinces the players that we are on the right way but we still have room for improvement."
Speaking about the central defence partnership Shkodran Mustafi and Laurent Koscielny, Wenger said: "I think they had an outstanding performance, both of them are committed and intelligent, technically sound so overall I am pleased."
October 2011 was the last time the Gunners manager celebrated three points from this particular London derby and Arsenal had not even scored in the league against their rivals since January 2013 - but Wenger and his side were soon on their way to addressing that issue.
The hosts had flown out of the traps and were ahead as Cahill dallied in possession, with Sanchez nicking the ball off his toe, racing clear and lofting a smart finish over Courtois.
And their pacey start to the game continued as they doubled their advantage within three minutes, Walcott tapping home Hector Bellerin's cross after a slide-rule pass from Alex Iwobi.
Branislav Ivanovic nearly added to the defensive woes for Chelsea as his attempted clearance was blocked into the feet of Sanchez, who could only shoot tamely wide having opted not to pick out Walcott.
Chelsea looked threatening when they could muster an attack and Willian arrowed a shot across Petr Cech and wide after tenacious work from Eden Hazard.
But it was the hosts who would strike again before the interval as Ozil broke forward and found Sanchez, who lofted a ball to the back-post where the Germany international arrived to hit a volley into the ground and over Courtois.
Hazard flashed a shot into the side-netting as former Chelsea stopper Cech punched a free-kick into the Belgian's path, but the first half belonged to Arsenal.
The Gunners started where they left off after the interval as substitute Granit Xhaka freed Walcott down the right and the England international's cross was only inches too high for Sanchez to nod home.
Antonio Conte reacted by changing the shape of his side, introducing Marcos Alonso in place of former Arsenal man Cesc Fabregas and shifting to play 3-4-3.
But, after losing 2-1 to Liverpool last weekend, the Italian has now suffered back-to-back league defeats for the first time since 2009 and has plenty to address at Stamford Bridge.
Wenger's men have now won their last four in the league and are unbeaten in all competitions since the opening weekend of the season as he looks to usher in his 21st year in style.
The result leaves Chelsea eighth in the table after six games and already eight points behind league leaders Manchester City.
"If someone thinks this season is easy, we must work a lot to improve and change the situation because now we are a great a team on the paper, not on the pitch," Conte said.
"I prefer to be a great team, not on paper, but also on the pitch because the pitch speaks the truth, the pitch is the most important thing for us. Not the words, not the paper. We must change this.
"Last season was a bad season and last season we were a great team on the paper. This team we want to be a great team also on the pitch.
"There are many difficulties but if we understand this we are in a good position to recover and to change the situation."
No team in the top half of the Premier League has conceded more than Chelsea's nine goals so far and they have now let in nine in their last four in all competitions.
Conte switched from a back four to a back three in the second half in hope of an improvement but the damage was already done.
"I think I have to solve the situation," Conte said. "The situation is every game we have conceded two goals at a minimum. For this reason, two back, three back or four back, I don't care.
"It's important to solve the situation. This is the most important thing. I must find the solution and I work a lot to find the right solution."
Chelsea's defensive woes once again bring to the fore the absence of John Terry, who was not declared fit enough to feature as he completes his recovery from an ankle ligament injury.
"John is recovering from a bad injury but I don't like to talk about players that today didn't play," Conte said. "I don't like this. I think this is a lack of respect for the players today who played bad or good."
