Elsewhere, Liverpool finally managed an overdue first league win of the season, while Manchester United also recorded a welcome victory after a difficult few weeks.
As City manager Nick Cushing’s departure to MLS draws closer, his team stretched their winning run to four WSL games by seeing off Birmingham in a comfortable 2-0 away victory.
England star Ellen White needed just 34 seconds to break the deadlock against her struggling former club, while Keira Walsh doubled the advantage in the second half with a looping effort from the edge of the penalty area that cannoned in off the post.
The loss, combined with others results, leaves Birmingham just one point off the bottom.
The three points sent City top because Chelsea stopped previous leaders Arsenal in their tracks. Emma Hayes’ side were fancied to get something owing to their strong recent record in away games against the Gunners, but even optimistic fans couldn’t have predicted what happened.
Chelsea, who haven’t lost a WSL away game against any team since May 2017, stormed the contest and raced into a 3-0 lead within the first 20 minutes. Beth England scored the first, followed by Sam Kerr’s maiden goal in English football. The third from Sophie Ingle, a precision left-footed half volley that flew into the top corner, is a contender for goal of the season.
Guro Reiten made it four for Chelsea, with Beth Mead grabbing an Arsenal consolation.
Chelsea remain third in the WSL table, despite their emphatic win. But now they are only a point behind both City and Arsenal – the former is top on goal difference – and have a game in hand.
Away from the title race, the big news of the weekend was that Liverpool won a WSL game for the first time this season, coming at the 12th attempt. The Reds, who bizarrely have the fifth best defensive record in the whole division, scored only their fourth goal of the campaign through winter signing Rachel Furness and kept a clean sheet to beat Bristol City 1-0.
Liverpool, who also had goalkeeper Anke Preuss to thank for saving a penalty to preserve the lead, moved out of last place as a result, pushing Bristol into the drop zone instead.
Manchester United have a troubled few weeks after frustrating postponements either side of a shock defeat to Bristol City in their opening game of 2020. But Casey Stoney’s Red Devils blew off some of the cobwebs to beat Tottenham 3-0.
It was a lacklustre first half from United in foggy conditions, but a penalty and free-kick from captain Katie Zelem either side of Jess Sigsworth tap-in secured the three points. Spurs did hit the woodwork twice in the second half, while Ella Toone was sent off for United late on.
The result put United back into fourth place, while Everton also won to climb to fifth. The Toffees were inspired by a Chloe Kelly hat-trick against Reading to end a run of three straight defeats.
Fara Williams scored for Reading to cancel out Everton’s first half lead, but two more Kelly goals after half-time secured all three points for the home side.
West Ham beat Brighton to put themselves back in touching distance with the league’s middle pack and establish more distance from the bottom of the table.
For a long time, it was the Seagulls who looked to be heading for a rare win when Danique Kerkdijk scored in the first half. B
The WSL will now pause until Sunday 2 February to make way for the Women’s FA Cup fourth round next weekend (25/26 January). An enticing derby clash between Manchester United and Manchester City is the pick of the ties to look out for.