Match ends, Chelsea FC Women 0, Arsenal Women 5.
Arsenal maintained their 100% start to the Women's Super League season with a stunning away win over Chelsea.
It was the reigning champions' first WSL defeat since May 2017 - and first at home since July 2016.
Kim Little put Arsenal ahead from the spot after Emma Mitchell was fouled and Vivianne Miedema slotted in the second.
Jordan Nobbs' cross flew over Carly Telford to increase the lead and her first-time finish rounded things off after Miedema had netted her second.
- Man City hit seven against West Ham
- Birmingham end Bristol City's unbeaten start
- Relive Sunday's WSL action as it happened
The closest Chelsea came to a goal was when Ramona Bachmann's ball into the box rebounded off the angle of post and bar in the first half.
And not even the prolific England striker Fran Kirby could find a way past impressive Arsenal keeper Pauline Peyraud-Magnin.
She kept out a 25-yard free-kick by Ji So-Yun and saved well from Bachmann in the early moments of the second half, with Drew Spence unable to force the loose ball home and reduce the deficit to 2-1.
Had she done so, Chelsea may have been able to take something from the game, but after Nobbs' fortunate first, Beth Mead provided assists for two more as Arsenal took their goal tally to 33 in all competitions so far this season - nine of them by Miedema.
Arsenal goalscorer Jordan Nobbs:
"I don't want to get too ahead of ourselves. I think we've been performing in every single game and it's no coincidence that we played well after our last few performances.
"It's not easy coming to Chelsea and playing against top players so I think it's credit to every single individual out there because they put in a shift and the quality of our finishing was brilliant again.
"Naturally it's a big statement but I think [we] know how quickly the league can change and how quickly points can be dropped in games. It's great for our confidence and our belief but we still need to take every game as it comes because we have got a lot of tough challenges ahead."
Chelsea boss Emma Hayes:
"I thought we were dominant up until the (opening) goal, but at this level you have got to take the first one.
"I've had more good days in football than bad. As far as I'm concerned this is a part of the journey.
"We have to sit here and say that our team had gone 25 games unbeaten - we haven't been beaten for a long time in that regard."
- 7CarterSubstituted forBlundellat 73'minutes
- 20AnderssonSubstituted forRileyat 59'minutes
- 24SpenceBooked at 63mins
- 17EngmanSubstituted forCuthbertat 55'minutes
- 10LittleSubstituted forMcCabeat 65'minutes
- 7van de Donk
- 23MeadSubstituted forSamuelssonat 86'minutes
- 1van Veenendaal
- Sam Purkiss
- Shots on Target
Second Half ends, Chelsea FC Women 0, Arsenal Women 5.
Corner, Chelsea FC Women. Conceded by Dominique Bloodworth.
Attempt missed. Ramona Bachmann (Chelsea FC Women) right footed shot from the right side of the box is close, but misses to the left. Assisted by Ji So-Yun.
Substitution, Arsenal Women. Jessica Samuelsson replaces Beth Mead.
Attempt missed. Magdalena Eriksson (Chelsea FC Women) header from the centre of the box misses to the left. Assisted by Erin Cuthbert following a set piece situation.
Ji So-Yun (Chelsea FC Women) wins a free kick in the attacking half.
Foul by Katie McCabe (Arsenal Women).
Attempt saved. Erin Cuthbert (Chelsea FC Women) right footed shot from outside the box is saved in the bottom left corner.
Substitution, Chelsea FC Women. Hannah Blundell replaces Jessica Carter.
Offside, Arsenal Women. Beth Mead tries a through ball, but Vivianne Miedema is caught offside.
Jessica Carter (Chelsea FC Women) wins a free kick on the right wing.
Foul by Katie McCabe (Arsenal Women).
Offside, Chelsea FC Women. Carly Telford tries a through ball, but Ramona Bachmann is caught offside.
Goal! Chelsea FC Women 0, Arsenal Women 5. Jordan Nobbs (Arsenal Women) right footed shot from the right side of the box to the bottom right corner. Assisted by Beth Mead following a fast break.
Francesca Kirby (Chelsea FC Women) wins a free kick in the attacking half.
Foul by Daniëlle van de Donk (Arsenal Women).
Attempt missed. Erin Cuthbert (Chelsea FC Women) right footed shot from outside the box is high and wide to the left. Assisted by Ji So-Yun.
Foul by Erin Cuthbert (Chelsea FC Women).
Lia Wälti (Arsenal Women) wins a free kick in the defensive half.