- Sam Kerr (23')
United started the day top of the WSL but their winless run against Chelsea extended to seven games, including six defeats.
Played in behind, Matildas star Kerr missed two clean chances to give Chelsea the lead in the opening 15 minutes before getting the better of Mary Earps at the third time of asking in the 23rd minute.
The Australia international was well found by Lauren James' floated ball over the top, and she chipped the ball over the Lionesses' No. 1 to give Chelsea the upper hand.
Alessia Russo had a great chance to put United level 12 minutes later but her snap shot flew straight at Ann Katrin Berger, and United also had a strong penalty appeal turned down when Nikita Parris was brought down by Kadeisha Buchanan.
The hosts fashioned a few half-chances after the break but, with their finishing found wanting, the door remained open for the visitors who pushed for an equaliser but could not get the better of Chelsea's resolute defending.
With 15 games played each, Chelsea have 38 points and are three ahead of United who have 35.
Elsewhere on Sunday, Manchester City continued their bid for a top-three finish thanks to a last-minute winner from Bunny Shaw as they beat Brighton and Hove Albion 2-1.
City are now just two points off of the top spot and only behind rivals United on goal difference.
Goals by Rachel Daly and Jordan Nobbs helped Aston Villa extend their unbeaten run in the WSL to six matches with a nervy 2-1 win at West Ham United.
Daly -- who is now up to 11 goals for the season, hunting down City forward Shaw in the golden boot race -- opened the scoring on 34 minutes and Nobbs added a second after half time with a close-range finish. Viviane Asseyi nodded home 11 minutes from time but her effort proved only a consolation.
Liverpool overcame Rosella Ayane's early goal to beat Tottenham Hotspur 2-1 at Prenton Park and send Rehanne Skinner's side closer to the relegation zone.
Spurs were unable to contain their high-pressing opponents and succumbed to two first half goals by Emma Koivisto and Missy Bo Kearns. The hosts were able to see out their one-goal lead to extend Spurs' struggles, with the north London club just two points from the relegation zone.
Bottom-of-the-table Leicester City moved to within one point of their relegation rivals Brighton with a hard-fought 0-0 draw at home to Everton.
With chances at both ends, it was Leicester's loanee goalkeeper Janina Leitzig who stole the show, making a pair of impressive saves in the second half to keep Leicester alive and kicking in the league.
Having bested Reading 4-0 in two of their last three meetings with the Royals, there was a predictability about the final score in the last game of the weekend when Arsenal hosted Reading.
Given an early boost with a fourth minute penalty awarded after some light contact in the box, the hosts doubled their advantage late in the first half when Frida Maanum fired home from close range.
Two became three just after the break when Maanum bore down on goal only for Emma Mukandi to get the last touch and send the ball beyond her own goalkeeper.
Leah Williamson rounded out the rout 20 minutes from time when she tucked home at the back post to wrap up all three points and leave Arsenal three shy of second with a game in hand on the two teams above them.
- Cheryl Foster