Birmingham came from behind to win at 10-player West Ham and move to within two points of third-placed Chelsea in the Women’s Super League table.
The match hinged on the sending off of Irons keeper Anna Moorhouse just before half-time for handling outside the box.
Wales international Hayley Ladd curled in the resultant free-kick to cancel out Adriana Leon’s close-range volley.
Chloe Arthur punished an error from substitute keeper Becky Spencer at a corner to complete the turnaround.
The Scotland midfielder was in the right place to smash in her first league goal for Blues after Spencer failed to gather Ladd’s high looping corner.
Birmingham’s second win in a row meant they took full advantage of Chelsea’s WSL absence this weekend, with Emma Hayes’ side instead in Champions League semi-final action against Lyon.
It is back-to-back defeats for mid-table West Ham, whose climax to the season takes place at Wembley next month when they face Manchester City in the FA Women’s Cup final.
Despite playing more than half of the game a player short, they pushed Birmingham hard.
After going ahead when Kate Longhurst’s left-wing cross was turned home by Canada forward Leon, West Ham were on the verge of a half-time lead before Moorhouse’s error and Ladd’s brilliant strike provided a crucial double blow.
Matt Beard’s team defended stoically after the break, Brooke Hendrix and Gilly Flaherty both clearing off the line in a frantic few seconds following another Ladd set-piece.
But they could not quite hold out as Arthur’s emphatic finish made sure Blues took home three points.