Olivia Smith scored the winning goal as Arsenal delayed Manchester City's pursuit to the Women's Super League title by beating the leaders 1-0 at the Emirates Stadium.
Defeat for City means Andree Jeglertz's side's winning run of 13 matches comes to an end - with Renee Slegers still unbeaten at home as Arsenal head coach.
With Stina Blackstenius missing, record-signing Smith was given the striker spot by Slegers for Arsenal and delivered on the faith put in her by opening the scoring on 17 minutes.
The Gunners forward was played in after a lovely through ball by Mariona Caldentey, before rounding Ayaka Yamashita to score.
League leaders City, who began the weekend with an 11-point advantage over the chasing pack, failed to show the firepower that has made them the league's top scorers with only one shot on target across the 90 minutes. That came via a tame first-half Bunny Shaw effort which was easily dealt with by the returning Daphne van Domselaar.
Arsenal continued their dominance of the first half as Alessia Russo saw two goalbound efforts saved by Yamashita, while Katie McCabe and Caldentey put efforts just wide.
The second half was a slightly different story, with half-time substitute Sam Coffey giving City more of a bite in midfield.
There was controversy though as Caldentey brought down Lauren Hemp with the City winger through on goal. Yet referee Abi Byrne continued play and Caldentey avoided punishment.
"I haven't seen it afterwards, so I don't know," said City boss Jeglertz. "But at the moment I'm very frustrated because I felt really that it was a clear free-kick.
"The fourth official was saying that it was their player who touched the ball, so I can't argue about that because I haven't seen it. But at the moment when it happened, I was annoyed because I think that was a clear free-kick."
Replays showed Caldentey did not get a touch on the ball.
City continued their push for an equaliser as Vivianne Miedema went through on goal. But a mixture of indecision and superb McCabe defending denied her a goal against her former club.
The result sees City hold an eight-point lead over second-placed Manchester United - with a derby match between the pair still to come this season. Arsenal sit 10 points off City with a game in hand over the league leaders - against Leicester later in the season.
Man City head coach Andree Jeglertz:
"Coaches don't really like to lose, but at the same time, today we played against Arsenal who were very good.
"We struggled a lot, especially in the first half, managing all their rotations and how they overloaded us in different areas. We didn't really nail that.
"The second half was better, I think we sorted it better. I also like how we ended the game. I think there were a lot of things in the last 10-15 minutes that showed that we were really pushing it, but it was too late.
"I think that [people saying City have already won the league] is not going to affect the players. We are fully aware of the situation we are in and we are still in a very good position in the league. We are still confident in what we have done so far."
Arsenal head coach Renee Slegers:
"It started growing in the week. We have been very successful with Stina in the nine [position]. I think she's so good with her physicality and her speed. She wasn't available so we wanted similar qualities even though Olivia and Stina are very different players.
"Liv had two, two-and-a-half trainings in the nine position. There were a lot of meetings with coaches, giving her the detail without getting too much information in her head.
"She could still play on intuition because that's when she's really good. She picked up the ball brilliantly and the goal was exactly what we wanted to create."
Your Site' Sam Blitz at the Emirates Stadium:
Since the winter break, Arsenal have played Man Utd, Chelsea and now Man City in the WSL - remaining unbeaten in all three and not conceding a single goal.
Even the best attacking team in the league could not break down the sturdy Gunners backline. Shaw barely had a sniff, the exciting Kerolin was subbed off with 20 minutes to go and while Miedema looked City's most threatening player, she did not manage a shot on target.
The league title may have gone but this defensive solidity from Slegers' side has multiple benefits elsewhere.
Firstly, the unbreakable centre-back partnership of Steph Catley and Lotte Wubben-Moy also allows Leah Williamson to take her time in coming back to recover. England's captain and Arsenal's star defender can take the necessary steps so she can really come back to her best.
It sets them up brilliantly for the resumption of the Champions League - the superb defensive attitude that even stopped Barcelona from scoring in last season's final remains.
This win over City - the best team in the country - shows Arsenal will always stand a chance in any game while they have this defensive solidity.
