Arsenal Ladies moved to within two points of Women's Super League One leaders Chelsea thanks to a narrow victory at winless Birmingham.
The hosts saw Freda Ayisi sent off for two bookable offences in a goalless first half.
Arsenal took the lead after the break through Chioma Ubogagu's fourth league goal of 2015.
Remi Allen hit the woodwork as Birmingham searched for an equaliser but the visitors held on.
The result moves the Gunners back up to second, while the Blues remain seventh, just one point above bottom club Bristol Academy.
Birmingham goalkeeper Rebecca Spencer twice saved well to deny Natalia, before Ayisi saw red with two yellow cards in quick succession - first for a foul on the Spain forward and secondly for an over-the-ball challenge on Leah Williamson.
The visitors capitalised after half-time when Ubogagu played a neat one-two with Natalia before finishing low in the bottom corner.
Blues almost equalised when Allen turned Karen Carney's cross onto the woodwork, before Kirsty Linnett volleyed the rebound over for the hosts, who are still yet to score a home league goal this season.
Arsenal Ladies boss Pedro Martinez Losa told BBC Sport:
"I think every game in this league is very, very competitive and very difficult. Today we solved it very well.
"The three points is important for motivation for the girls.
"Now we have a very important mental moment, getting closer to Chelsea and sending a message to everybody that we are going to be competitive for the league."
Birmingham City: Spencer, Sargeant, Carter, Mannion, Harrop, Ayisi, Allen, Carney (c), Potter (Linnett 45 (Wellings 87)), Moore, Lawley.
Subs not used: Wellings, Edwards, Westwood, Windell, Haines, Peplow.
Arsenal: Byrne, Scott (c) (Carter 45), Mitchell, Stoney, Losada (Bailey 78), Natalia (Yankey 73), Ubogagu, Williamson, Corridera, Rose, Janssen.
Subs not used: Van Veneendal, Humphrey, Kelly, Clarke, Bailey.
Referee: Ollie Yates.