The five-time winners went ahead after 18 minutes, though it was United who dominated the opening exchanges. Jess Sigsworth was a constant menace on the right and worked an opening for herself with a touch around her marker and a driving run into the box but her low, drilled shot went just wide.
Arsenal’s first real opportunity resulted in the opening goal. Miedema latched onto an inch-perfect pass to poke past the onrushing Siobhan Chamberlain - a clinical finish by WSL’s top goalscorer.
The home side dominated possession after the goal and could have had a second if not for Katie Zelem’s excellent clearance just before half-time.