Arsenal deservedly beat Chelsea 2-0 in Saturday's Premier League clash at the Emirates Stadium to enliven the race for Champions League qualification.
Unai Emery had said on the eve of the game that a defeat at the Emirates Stadium, which would have left Arsenal nine points adrift of the fourth-placed Blues, would have meant the end of their top-four ambitions.
In truth, the hosts never looked like losing as they went at Chelsea from the off, sealing the win with first-half goals from Alexandre Lacazette and Laurent Koscielny.
Maurizio Sarri opted to set up his Chelsea side with Eden Hazard again playing at the main central attacking option and the visitors rarely threatened.
Mesut Ozil returned to the Arsenal squad having been dropped for the loss at West Ham, but Emery left the German on the bench - with a serious-looking knee injury to Hector Bellerin the only negative for the Gunners.
They were lively in the early goings as Emery's midfield diamond caused problems for the Chelsea defence, with Pierre-Emerick Aubameyang missing a fine chance to open the scoring as he fluffed his lines following a low Lacazette cross.
When Arsenal did hit the target through a Koscielny header, it was up to Chelsea goalkeeper Kepa Arrizabalaga to make a superb reaction save to deny the fit-again skipper.
But there was nothing Kepa could do moments later as Lacazette deservedly put Arsenal in front with a vicious finish from Bellerin's cross.
Arsenal maintained the momentum which led to their opening goal as Aubameyang stole the ball after a Cesar Azpilicueta slip - but he was closed down well before poking an effort at Kepa.
Chelsea finally responded as Pedro stole in behind the Arsenal defence to reach David Luiz's pass and lob an effort over the onrushing Bernd Leno only to see the ball drop inches wide.
The second goal came six minutes from half-time as a well-worked free-kick led to Sokratis firing the ball back into the box, where Koscielny had stayed onside to convert past Kepa off his shoulder for his first goal since last February.
Marcos Alonso headed against the post as Chelsea ended the half strongly, although it was Arsenal who went in ahead - just the third time Emery's side have managed to do so in the league this season.
Chelsea picked up where they left off after the interval but, with no recognised striker on the pitch, their attacks were being mopped up by the Arsenal defence.
Pedro fired over and Alonso wide but Leno remained untested as the game entered the final 30 minutes - with Sarri turning to Ross Barkley, and then former Arsenal striker Olivier Giroud, in search of a goal.
Arsenal's evening was tainted as Bellerin, starting for the first time since a calf injury, was carried off on a stretcher having gone down holding his knee.
Chelsea pushed further forward in the hope of a spectacular comeback but never came close to reducing the arrears as Arsenal returned to winning ways.
Opta match facts
- Arsenal have won consecutive home games against Chelsea in all competitions for the first time since February 2004.
- Chelsea have only won one of their last seven away London derbies in the Premier League (D2 L4), winning 1-0 at Crystal Palace in December.
- Arsenal are unbeaten in 13 Premier League London derby matches at home (W10 D3), winning the last six in a row.
- Arsenal have won more points in seven games against ‘big six’ sides this season (8) than they did in the whole of the 2017-18 campaign (6).
- Chelsea’s first shot on target didn’t come until the 82nd minute, from Marcos Alonso.
- 63% of Arsenal striker Alexandre Lacazette’s Premier League goals this season have come in London derbies (5/8).
- Only Arsenal teammate Pierre-Emerick Aubameyang (6) has scored more Premier League London derby goals this season than Alexandre Lacazette.
- Laurent Koscielny became the first Arsenal defender to score 20 Premier League goals. The Frenchman has scored in each of his nine campaigns in the competition – only Dennis Bergkamp (11), Aaron Ramsey and Theo Walcott (10 each) have scored in more for the Gunners.