Chelsea scored two goals in four minutes to end Manchester United's perfect start to the Women's Super League season at Leigh Sports Village.
United had won five consecutive games without conceding a single goal.
But one sloppy passage of play gave Sophie Ingle the opportunity to pick out Sam Kerr, who fired her shot into the bottom corner past goalkeeper Mary Earps.
United were opened up again when a long ball got behind the defence and found Kerr in space on the edge of the area and Lauren James coolly converted her simple pass.
United pulled one back through Alessia Russo's swept shot but Erin Cuthbert sealed the deal for Chelsea in injury time.
Chelsea move level on points with Arsenal at the top of the WSL while United drop to third.
Chelsea show experience and class
Defending champions Chelsea, going for their fourth consecutive WSL title, came into this game with five straight wins under their belt and showed their experience against a United team searching for their first ever top-three finish.
Although the first half didn't present many clear-cut opportunities, they were more comfortable on the ball and seemed happy to keep pegging United back.
The Blues had an early shout for a penalty when Maya Le Tissier caught Guro Reiten just inside the area - but it did look like a slip and, perhaps coupled with Reiten's lack of appeal, the referee didn't see enough for a spot-kick.
Chelsea came close when Niamh Charles looped in what at first seemed like a cross but Earps had to be alert as her fingertip save kept it out and a searching Cuthbert cross made its way to Kerr who volleyed across the box to Pernille Harder, whose header was just wide.
Cuthbert, who had been fairly quiet, took her chance when it came and her deflected shot capped off a professional performance where the Blues could have probably scored more.
Defending champions Chelsea remain without manager Emma Hayes as she continues to recover from a hysterectomy but showed their class to execute a professional performance.
Blow to United's impressive start
It could be said that United, who have made an impressive start to the season and put themselves in the conversation as title-contenders, have not yet been asked real questions when it comes to their defence and form against the top sides.
They have put in stellar performances, but this result puts a dent in not only United's unbeaten start to the season but perhaps also their confidence when faced with top sides.
After a tricky first half United started the second much brighter as their attempts to unlock the Chelsea defence improved.
But Chelsea's first goal was a sloppy one for United to concede and having shipped no goals in five games it clearly rocked the confidence of what had, up until then, been a solid defence.
Maria Thorisdottir passed the ball straight to Ingle deep in United's half and it was all too easy for Kerr to finish the move one-on-one with Le Tissier.
United showed their lack of experience in what is their first real test of the season when they conceded again less than four minutes later.
But, buoyed by a record crowd of 6,186 at Leigh Sports Village, Toone released Russo after Chelsea carelessly gave the ball away to pull one back.
The flurry of action gave United a boost as Hayley Ladd saw her decent effort from range sail over and Russo once again went close.
But while the result showed vast improvement on last season's 6-1 thumping in the same fixture last season, Chelsea's quality and experience shone through.
