After putting nine past Charlton three days earlier, Arsenal struggled to find the net against a weakened Birmingham City. However, Jayne Ludlow's late goal earned a 1-0 win and left the champions within touching distance of another Premier League title.
Birmingham were missing five first-team regulars but battled gamely to keep out their in-form opponents. Arsenal created a number of chances but didn't really trouble the Blues keeper.
A draw looked on the cards as time ticked away but substitute Ludlow, with her first touch of the ball, headed home England winger Rachel Yankey's 85th minute corner.
With a 100 per cent record to date, the five points Arsenal need to clinch the title from their remaining five games should be a formality.