Marcos Alonso's late goal gave Chelsea a 3-2 win over Arsenal in a frantic encounter in Maurizio Sarri's first competitive game at Stamford Bridge.
Alonso swept home from close range after being found by sub Eden Hazard, meaning Unai Emery's Arsenal have lost two from two this season.
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There were four goals in a dramatic first half. Pedro (9) and Alvaro Morata (20) capitalised on woeful Arsenal defending to put Chelsea 2-0 up, as both Pierre-Emerick Aubameyang and Henrikh Mkhitaryan missed sitters for the visitors after each goal.
Chelsea: Kepa (5), Azpilicueta (5), Rudiger (4), Luiz (4), Alonso (7), Kante (6), Jorginho (8), Willian (6), Barkley (7), Pedro (6), Morata (7)
Subs: Kovacic (6), Hazard (7), Giroud (6)
Arsenal: Cech (7), Bellerin (3), Sokratis (4), Mustafi (4), Monreal (5), Xhaka (3), Guendouzi (5), Mkhitaryan (6), Ozil (4), Iwobi (6), Aubameyang (6)
Subs: Torreira (6), Ramsey (6), Lacazette (5)
Man of the match: Jorginho
But Arsenal found themselves level at the break through Mkhitaryan's 20-yard effort (37) and Iwobi's close-range finish (41), with both sides visibly neglecting their defensive duties.
Arsenal crumbled again late on to allow Chelsea the winner, continuing the Blues' 100 per cent start in the Premier League under Sarri.
Chelsea initially had the run of Arsenal and were ahead through Pedro as Hector Bellerin was caught high up the pitch, allowing Alonso acres to square for his Spanish compatriot in even more space. He duly swept past former Blues goalkeeper Petr Cech.
Eden Hazard started on the bench with Chelsea unchanged following the win over Huddersfield.
Arsenal made two changes; Nacho Monreal replaced the injured Ainsley Maitland-Niles, and Alex Iwobi was in for Aaron Ramsey.
Aubameyang was head-in-hands just after, blazing over from eight yards from Bellerin's centre, and it was 2-0 just 55 seconds later after Morata was left one-on-one with Shkodran Mustafi from Cesar Azpilicueta's simple ball from deep.
Morata wrestled Mustafi away, before sliding past Cech as Arsenal fans got a case of déjà vu at Stamford Bridge, where they now haven't won in eight.
Mkhitaryan blazed over at the other end in a similar position to Aubameyang, but the Armenian made up for it with a fierce drive from the edge of the box, despite Kepa Arrizabalaga getting a touch.
Arsenal levelled through Iwobi's slammed finish from 10 yards, picked out by Mkhitaryan after Chelsea gave him the freedom of west London, and Emery's side would have gone into half-time ahead if the Nigerian hadn't blazed over from near the penalty spot in space again.
Space was handed out in abundance again after the break; Kepa was down low to save from Aaron Ramsey's effort, while N'Golo Kante headed just over at the other end, but Chelsea got their winner with nine minutes remaining.
Sub Hazard danced past Alexandre Lacazette with ease on the left, before finding Alonso eight yards out to sweep through Cech's legs.
It would have been worse for Arsenal had Cech not kept out Hazard and former Gunners striker Olivier Giroud twice late on, but it ended 3-2 on an evening which showed neither defence in good light.
Man of the match - Jorginho
In a game lacking in defensive discipline of any kind, this was a difficult award. But Jorginho's showing, alongside a clearly energised Ross Barkley, was superb.
He won the ball a team-high nine times, touched the ball a match-high 105 times, and made 99 passes at 91.6 per cent completion, with 56 in the opposition half.
Chelsea fans like what they've seen so far, and they can expect more of the same to come.
Notes for Southgate
Barkley's clear rise in confidence can only be a good thing for England and Gareth Southgate. In his 60 minutes, Barkley was happy to drive at a struggling Arsenal defence, and came close to scoring when his angled shot was tipped wide by Cech. This was more like the Barkley of old.
- Chelsea have won six of their last seven home league games against Arsenal, the exception being a 0-0 draw last season.
- Arsenal scored two goals against Chelsea, as many as on their previous six Premier League visits to Stamford Bridge.
- Unai Emery is the first Arsenal manager to lose his first two games in charge since Steve Burtenshaw, who lost his first three in charge as caretaker in March/April 1986.
- Chelsea winger Pedro has scored in consecutive Premier League games for the first time since February 2017.
Arsenal now face West Ham at the Emirates on Saturday, while Chelsea go to Newcastle on Super Sunday at 4pm, live on Sky Sports Premier League.