Arsenal Ladies slipped to their first defeat since the mid-season break on Wednesday, losing 2-1 to Chelsea Ladies.
The Gunners came into this London derby on the back of a five-game unbeaten streak but this defeat means they remain second bottom of the Women's Super League.
After creating the better openings in the first half, Arsenal fell behind at the start of the second half through Yuki Ogimi before Ji So-Yun's free-kick sent Chelsea further clear.
Kelly Smith's penalty halved the deficit with 25 minutes to go but the visitors couldn't complete a dramatic comeback despite piling on the pressure.
SETTING THE SCENE
John Bayer made one change to the team that saw off the Blues so convincingly in the Continental Cup earlier this month and three changes from Sunday's comfortable win over Millwall Lionesses.
Arsenal's two victories over Emma Hayes' side this season had come in cup competitions and they trailed the west Londoners by four points going into this game. But Arsenal were rejuvenated after their five-match winning streak under their interim coach.
It was Bayer's team who made the better start and registered their first attempt on goal after five minutes when Alex Scott rolled an effort wide.
Chelsea responded and almost took the lead when Hannah Blundell found space inside the box but Casey Stoney made a well-timed block.
In the 26th minute former Gunner Katie Chapman tried to lob Byrne from distance but her effort flew harmlessly over.
The first big opportunity of the game fell to the Gunners on the stroke of half-time when Danielle Carter rounded Marie Hourihan but directed her shot wide.
Bayer's side continued to probe after the restart and some neat interplay between Carter and Smith almost set up Ohno, but Smith's flick-on just evaded the Japanese forward.
Despite having the territorial ascendancy, Arsenal fell behind in the 51st minute when Ogimi sent a lobbed volley over Byrne.
Chelsea doubled their lead in the 64th minute when So-Yun placed home a free-kick after Niamh Fahey had bought down the South Korean.
Arsenal were given an immediate lifeline when they were awarded a penalty for a handball which Smith duly converted.
Bayer threw on Yankey who saw a free-kick saved by Hourihan before flashing an effort over as Arsenal pushed for an equaliser.
Former Gunners defender Gilly Flaherty was sent off in stoppage time after receiving a second yellow card but Chelsea held on to condemn their London neighbours to their first league defeat on the road this campaign.
- Fahey Yellow Card
- Smith Goal!
- Bailey 87
- Ohno 71
- Yankey 71
- Ayisi 87
- Blundell Yellow Card
- Flaherty Red Card
- Ogimi 76 Goal! Yellow Card
- Ji Goal!
- Rafferty 60
- Spence Yellow Card
- Williams 76
- Meiwald 60