Bottom-of-the-table Birmingham had goalkeeper Emily Ramsey sent off as they slipped closer to relegation from the Women's Super League with defeat by Leicester at St Andrew's.
Ramsey was shown a red card in the first half for fouling Jess Sigsworth, who then converted the penalty.
It soon got worse for Birmingham when Jemma Purfield's corner went in.
Louise Quinn fired home at the near post late on to give the hosts hope, but they could not find an equaliser.
Instead, Leicester went closest to adding a third in injury time when Sigsworth hit a post before Paige Bailey-Gayle's shot from the loose ball was headed off the line.
Defeat left Birmingham five points adrift of second-bottom Leicester.
The result will have been all the more frustrating for the hosts because they started the game well, nullifying Leicester's threat until the pivotal moment when striker Sigsworth charged through on goal and Ramsey brought her down.
Substitute goalkeeper Lucy Jones was beaten by Sigsworth's penalty and Leicester took full advantage of the tactical disruption caused by Ramsey's dismissal by adding a second before half-time, Purfield's curled delivery from a corner going all the way into the net.
Birmingham showed plenty of fight in the second half and deservedly got a goal back late on through Quinn.
Birmingham, who have won only one of their 14 games this season, have eight games in which to save their WSL status.