Chelsea are one win away from being crowned WSL champions for a third successive season after the Blues battled to a narrow 1-0 win over Birmingham.
Emma Hayes' side struggled against a tenacious, relegation-threatened Birmingham, needing a second half Pernille Harder penalty to see them past the WSL's bottom side.
Chelsea exploded out of the blocks and twice came close to taking an early lead; Harder flashed a golden opportunity narrowly wide, and Sam Kerr rattled the bar inside the opening 10 minutes.
It was seemingly going to be a matter of when, not if Chelsea broke the deadlock, but Birmingham grew into the game and caused the visitors problems of their own, particularly from set pieces, and it finished goalless at the break.
Birmingham continued to frustrate Chelsea and looked like they could hang on to claim a point and provide another twist in the WSL title race. But in the 70th minute a Niamh Charles' header struck the arm of Lisa Robertson, and referee Emily Heaslip pointed to the spot. Harder cooly dispatched the subsequent spot kick.
Ann-Katrin Berger tipped over an Emily Whelan effort at the death as Chelsea hung on to a vital victory. The Blues will lift the WSL title at Kingsmeadow on Sunday if they get the better of Manchester United.
Birmingham vs Chelsea player ratings - WSL
1. Birmingham (3-5-2)
GK: Emily Ramsey - 6/10 - Made a really good stop to keep out Harder in the second half. A calming presence, hardly put a foot wrong.
RB: Abbie Cowie - 6/10 - Initially struggled against Reiten but grew into the game, venturing forward more as the game progressed. Replaced just after the hour - a sensible substitution given she was on a booking.
CB: Harriet Scott - 6/10 - Rolled by Harder on a couple of occasions, but largely did a stellar job frustrating Chelsea's usually lethal forward line. Made an important header to keep Spence out in the latter stages.
CB: Louise Quinn - 7/10 - An absolute rock at the back, throwing herself in front of anything and everything - including a tremendous block with her face to deny Eriksson from point blank range. Barely even winced.
CB: Gemma Lawley - 6/10 - A big defensive display up against Chelsea's illustrious forward line.
LB: Lisa Robertson - 5/10 - Conceded the penalty that led to Chelsea's opener with the ball striking her outstretched arm - didn't know a great deal about it.
CM: Jamie Finn - 5/10 - A battling display, but faded towards the end as Chelsea re-took control of the game.
CM: Christie Murray - 5/10 - Ran her socks off but like Finn faded in the final 20 minutes as Chelsea took the upper hand.
CM: Jade Pennock - 5/10 - A tenacious performance, but unable to have any real attacking impact on the match. Replaced just before the 70 minute mark.
ST: Veatriki Sarri - 7/10 - Carried Birmingham's greatest threat from open play, typically tricky and smart on the ball. Caused chaos with her set piece delivery.
ST: Lucy Quinn - 6/10 - A real battling performance, held the ball up well and sent Cowie away with a particularly impressive through ball in the second half.
Sub: Lucy Whipp - 5/10
Sub: Libby Smith - 5/10
Emily Whelan - N/A
2. Chelsea (3-5-2)
GK: Ann-Katrin Berger - 5/10 - Unconvincing from set pieces with Birmingham wreaking havoc from corners. Made a big save at the death to keep out Whelan.
CB: Magdalena Eriksson - 6/10 - Looked a threat from corners and won plenty in the air defensively.
CB: Jess Carter - 6/10 - Cool and tidy on the ball at the back - no mean feat considering the conditions. Replaced after 63 minutes.
CB: Millie Bright - 7/10 - Launched the ball forward time after time, mopped up well at the back. Made a big block to keep out Sarri in the second half.
RWB: Niamh Charles - 6/10 - Tirelessly up and down the right flank. Saw a lot of the ball in the first half and looked really dangerous, quieter in the second.
CDM: Sophie Ingle - 5/10 - Tidy in possession but didn't have a huge influence on proceedings, replaced after 63 minutes as Chelsea went in search of a winner.
LWB: Guro Reiten - 7/10 - Turned on the afterburners on a number of occasions to blitz down the left flank and create openings. Caused chaos with a couple of dangerous deliveries.
CAM: Jessie Fleming - 6/10 - Typically energetic and largely efficient in possession, bar one dangerous pass to gift Sarri possession in the Chelsea half.
CAM: Pernille Harder - 7/10 - Flashed a great chance across the face of goal in the opening exchanges. Picked out Charles with a beautiful through ball in the first half, cooly stroked home from the spot to give Chelsea the lead.
ST: Beth England - 5/10 - Hardly had a sniff of goal as Chelsea faded after an electric opening 10 minutes. Sacrificed at half time to allow Chelsea to switch shape.
ST: Sam Kerr - 5/10 - Cracked the bar inside the opening five minutes and skewed a half chance wide in the second.
Sub: Erin Cuthbert - 8/10 - Covered every blade of grass, worked back tirelessly on a number of occasions and fizzed with energy - the perfect half time substitution.
Sub: Jonna Andersson - 6/10
Sub: Lauren James - 7/10
Sub: Drew Spence - 6/10
Sub: Maren Mjelde - N/A