Manchester United began the game with a bang as Ella Toone slotted the ball past Brighton keeper Sophie Baggaley in the second minute after former Seagull Elizabeth Terland found her in space on the counter after Gabby George's accurate clearance from her own box.
The hosts were then able to double their lead after a short freekick from Toone near the corner found Miyazawa. The Japanese midfielder's initial shot hit team-mate Celin Bizet before Miyazawa got a second bite at the cherry and coolly slotted past Baggaley.
The visitors started the second half much better than they did the first as they managed to gain some momentum. However, they failed to reduce the deficit as former Manchester United striker Nikita Parris missed two key chances and failed to even test goalkeeper Phallon Tullis-Joyce. United soon grabbed their third of the game after Bizet nutmegged Jelena Cankovic before ripping a shot from 30 yards out to beat Baggaley. Marc Skinner's side then managed to see the game out comfortably, securing a well-deserved clean sheet and all three points.