Vivianne Miedema became the first player to reach 100 Women's Super League goal contributions as leaders Arsenal saw off Birmingham.
The highest scorer in WSL history, Miedema doubled Arsenal's lead with a cool first-half finish at Meadow Park.
Rafaelle Souza had opened the scoring and Beth Mead put Arsenal 3-0 up.
Libby Smith and Lucy Quinn gave Birmingham hope, but Caitlin Foord's late strike moved Arsenal eight points clear at the top of the table.
Arsenal last won the WSL in 2019 and this result gives them a handy cushion over reigning champions Chelsea, although Emma Hayes' side have three games in hand.
Arsenal boss Jonas Eidevall said: "We were in total control, playing well, then we conceded a goal and then another out of nothing. It looked like we just wanted the game to end.
"But you can't play football with fear and I'm happy we scored the fourth goal."
In Miedema, Arsenal have the league's crowning talent and she oozed class throughout. Her 100 goal contributions comprise 70 goals and 30 assists since her arrival in 2017.
While she described her 10th of the season as "an ugly goal", it is more than Birmingham had scored in total in the WSL this season before the game.
Arsenal's defeat by the Blues eight weeks ago was the shock result of the campaign, but it remains the only victory of a difficult season for Darren Carter's team.
Birmingham struggled to create anything yet found some spirit in the last 15 minutes to punish defensive complacency from their hosts, Smith bundling home and Quinn threatening a spectacular comeback with a fine finish.
Eidevall's side looked nervous as Birmingham hunted an unlikely point, but broke away and clinched the points as Foord fired home in stoppage time.
