Chelsea missed the chance to go back to the top of Women's Super League One as they were beaten at home by Manchester City.
England striker Toni Duggan curled in to give the visitors an early lead.
Chelsea levelled through Eniola Aluko's shot but Lionesses skipper Steph Houghton's late free-kick deflected in off Claire Rafferty to win it for City.
Defeat leaves Chelsea third after wins for leaders Sunderland and Arsenal, while City are four points off the top.
The visitors, who still have a game in hand on all of their WSL 1 title rivals, moved level on points with fourth-placed Notts County.
Duggan latched onto Daphne Corboz's through ball to fire City ahead early in the first half.
Chelsea, backed by a crowd of 1,857 - a record for the club at Staines Town - slowly grew into the game and levelled shortly after half-time thanks to Aluko's quick swivel and finish.
But Houghton's heavily-deflected strike inflicted a second consecutive league defeat on FA Cup finalists Chelsea, who had been unbeaten in all competitions before a 4-0 loss to Sunderland last weekend.
Chelsea Ladies boss Emma Hayes told BBC Radio 5 live sports extra:
"It was a cruel way to end the game. A draw would have probably been a fair result. It's important that the squad bounce back to get ready for Saturday.
"While everybody is licking their chops about us losing today, I promise you this league has got a long way to go."
Manchester City Women boss Nick Cushing told BBC Radio 5 live sports extra:
"All season we've played well, but we haven't turned those performances into results, but in the last four games we have.
"Now we seem to be scoring all over the pitch, and we're even getting the lucky ones like Steph (Houghton)'s goal today."
Chelsea Ladies: Lindahl, Blundell, Bright, Flaherty, Fahey, Davison (Borges), Aluko, Ji, Rafferty, Chapman (c), Spence (Coombs).
Subs not used: Hourihan, Brett, Meiwald, Banusic, Primus.
Manchester City Women: Bardsley, Bronze, Stokes, Beattie, Houghton (c), Scott, Duggan, Corboz (Johnston), Christiansen, Parris, Radtke.
Subs not used: Brooks, Lipman, Brougham, McManus.