Leaders Chelsea's record-breaking 33-game unbeaten run in the Women's Super League came to an end as they were stunned 2-1 by Brighton at Kingsmeadow.
After Manchester United's surprise defeat to Reading in the early kick-off, reigning champions Chelsea came out of the blocks quickly and opened the scoring after just five minutes. Sam Kerr looped a header over Megan Walsh from Erin Cuthbert's pinpoint delivery from a corner.
The lead lasted just two minutes, though, as Brighton equalised from a corner of their own. Aileen Whelan thundered a header past Carly Telford from Megan Connolly's centre.
Chelsea moved the ball sharply as they looked to restore their lead as the snow swirled around Kingsmeadow, but Brighton stuck to their task well and went in all square at the break.
With Hope Powell's Seagulls staying compact and battling hard, Emma Hayes turned to her bench 10 minutes into the second half.
Record signing Pernille Harder almost put the Blues ahead after 75 minutes but she could only hook the ball onto the right-hand post after good work down the left from Jonna Andersson.
Brighton won a corner from the resulting attack and took a shock lead when Telford could only palm Connolly's inswinging corner into her own net in the 77th minute.
Chelsea piled on the pressure in the closing stages but Brighton's heroic back-line stood firm and they headed back to the south coast with a hard-fought three points.
The Blues stay top of the table on goal difference but have a game in hand on United.
Earlier in the day, Manchester United missed the opportunity to go top of the Women's Super League table after a 2-0 defeat to Reading.
Goals from Danielle Carter and captain Natasha Harding handed the Royals just their second victory in the last 10 games.
After a tense first half, the visitors made the breakthrough when Harding was on hand to poke home the ball home after a goalmouth scramble from a corner.
The visitors made it two goals in as many minutes after Emma Mitchell's free-kick picked out an unmarked Carter who guided a header home.
Manchester City enjoyed a fruitful trip to London as they claimed all three points in a 2-1 win at Arsenal.
Ellen White and Lauren Hemp did the damage for City, while Australia international Caitlin Foord provided the Gunners with their only goal of the game.
White broke the deadlock 24 minutes in with a half-volley from inside the box, connecting perfectly with Chole Kelly's cross.
White's goal was her 55th in the WSL and she is now the league's all-time top scorer after edging ahead of Vivianne Miedema, who could not find the net for Arsenal on Sunday.
The home side were quick to retaliate through Dutch international Jill Roord, whose close-range goal was ruled offside after 36 minutes.
Foord equalised for Arsenal 12 minutes into the second half, but parity was short-lived as Kelly once again provided an assist - this time for Hemp, who thumped the ball into the back of the net with a header in the 79th minute.
The result lifts third-placed City seven points clear of Arsenal, who sit fourth with a game in hand.
Everton were unable to close the gap on the top four in WSL as they were held to a 1-1 home draw by Birmingham.
Danielle Turner gave the hosts the lead in the first meeting of the two sides this season after two postponements of the fixture, but Birmingham levelled through Jamie-Lee Napier at Walton Park.
Willie Kirk's Toffees made the breakthrough in the 22nd minute when Turner scored her first goal of the season with a 19-yard free-kick.
However, the visitors were level 10 minutes later. Goalkeeper Tinja-Riikka Korpela denied Claudia Walker from the penalty spot, only for Napier to react quickly and convert the rebound from close range.
Both teams gave debuts to new signings, with Jill Scott and Alisha Lehmann featuring for the Merseyside team and Arsenal teenager Ruby Mace in the Birmingham line-up.
Everton midfielder Megan Finnigan came closest to scoring in a goalless second half with a glancing 89th-minute header which struck the crossbar.
Although the hosts had plenty of possession, Carla Ward's side made sure of a point with another resilient defensive performance.
Matt Beard's return to West Ham saw his new side Bristol City take a point in a 1-1 draw.
It was the visitors who took the lead in the bottom-of-the-table clash in the eighth minute. Hammers midfielder Emily Van Egmond turned the ball into her own net from a Bristol City corner.
Ebony Salmon came close to extending the Robins' lead but her shot from the left-hand side of the penalty area came back off a post.
West Ham equalised in the early stages of the second half. Bristol City failed to clear Van Egmond's shot and the ball fell to Katerina Svitkova who slotted it into the right-hand side of the net.
Neither side could find a winner, with Laura Vetterlein's free-kick superbly tipped over the crossbar by Bristol City goalkeeper Sophie Baggaley, while at the other end Jemma Purfield's shot hit the crossbar.
The Women's Football Show
In the latest Sky Sports Women's Football Show podcast, former England captain Gillian Coultard reflects on her career and being awarded an MBE, while Chelsea forward Pernille Harder talks title ambitions and equality within the game.
Jess Creighton and Sue Smith are also joined by Sheffield United's Courtney Sweetman-Kirk to discuss Emma Hayes' being linked with AFC Wimbledon and the issue of diversity within the game.