Jane Ross' 50th-minute goal settled a hard-fought contest and kept the visitors seven points clear of closest rivals Chelsea Ladies, who were 3-0 winners at Reading Women.
Ross did not appear to know much about the goal, with England captain Steph Houghton's free-kick deflecting off her head as she sought to make a nuisance of herself in the Arsenal wall and looping beyond goalkeeper Sari van Veenendaal.
Manchester City, who have played a game more than Chelsea, can wrap up the title if they avoid defeat at home to the Blues when they meet in a fortnight's time.
Three second-half goals, two in stoppage time saw Chelsea keep their challenge alive.
Katie Chapman broke the deadlock in the 53rd minute and late efforts from Gemma Davison and Ana Borges added a touch of gloss to the scoreline.
Source : PA
Source: PA