Charlton and Leicester will face off on Saturday in the first-ever play-off for a place in the WSL next season, live on Sky Sports.
The Foxes finished bottom of the WSL table with just nine points, eight adrift of Liverpool in 11th, and will now travel to The Valley this weekend to keep their spot in England's top league.
Charlton, meanwhile, finished third in WSL2 behind Crystal Palace and Birmingham and can now earn promotion in the one-legged match.
Why is there a play-off?
The WSL is expanding to 14 teams from next season, a boost from the current 12 teams. It is just the first step on a 10-year plan to improve and grow the women's game in England.
Expansion improves competitiveness in the top league, where it was felt there were too many games that did not have any jeopardy or affect the league standings. It also offers an additional chance for teams in the WSL2 - many who have been battling for years for just one promotion spot - the chance to play in the WSL.
It also offers an incentive for teams in WSL2 to invest in their women's teams. WSL Football have introduced stringent licencing rules to raise the minimum standards as they aim to have two fully professional leagues.
However, it will add four more games to an already-congested fixture list - increasing from 22 to 26 - especially for those teams who also compete in Europe.
Crystal Palace and Birmingham have taken two of those spots, and the other will be determined by the play-off winner.
From the 2026/27 season, there will be one automatic promotion place in the WSL2, while the bottom side in the WSL will be relegated.
Then, the second-place WSL2 team and the 13th-place WSL team - second from bottom - will compete in a play-off for a place in the top league.
What has their form been like?
Neither side have been on a winning streak. Charlton will arguably feel they let automatic promotion slip through their fingers, having led the table for large parts of the season and had a point lead at the top heading into the final match.
However, they only won two of their last eight league games, and suffered defeats to promotion rivals Crystal Palace and, on the final day, Birmingham. They ultimately finished two points behind the promoted teams.
But they did go all the way to the FA Cup quarter-finals, where Liverpool needed extra-time to beat Charlton at The Valley.
Leicester, meanwhile, have lost their last 11 WSL matches and did not pick up any points in 2026. Their last win was on December 14 against London City Lionesses, beating them 1-0 at the King Power before the winter break.
However, despite some bruising defeats, there have been good performances, including against Chelsea in their penultimate WSL game.
While the Foxes have six days to prepare for Saturday's game, Charlton's last match was on May 2 - almost two weeks of added rest and preparation. Only time will tell if that will be a help or hindrance.
The rise of Leicester's teenage goalkeeper
If you want to talk about baptisms of fire, have a word with Leicester goalkeeper Katie Keane. The 19-year-old made her first team debut when she came on at half-time against Arsenal just over three weeks ago.
Replacing Olivia Clark, the Foxes were already 5-0 down after a riotous first half from the Gunners. Keane conceded two more in the second half.
The following week, her first start and full debut - against Chelsea. Despite losing 3-1, the teenager put in an assured performance, and it took a 96th minute goal against Everton to keep her from a clean sheet on Sunday.
Such is her rise, she does not even have a Wikipedia page, but it looks like Keane has cemented herself as Leicester's No 1.
She now faces the biggest game of her short career as she aims to keep Charlton out. Of the top six teams, the Addicks were the lowest scorers in the WSL2 this season.
Watch all three of Keane's performances for Leicester below...
Charlton: The former powerhouse aiming for top league return
Before the likes of Chelsea dominated English domestic football, Charlton were the most successful women's team in the country.
Starting as Bromley Borough, then Croydon Women FC, Charlton came under their current name after a takeover by the men's club in 2000. Up until 2007, the Addicks competed in numerous cup finals winning the League Cup twice and FA Cup once in 2005.
However, they were never able to win the then-league - known as the FA Women's Premier League National Division - before being controversially disbanded after the men's team were relegated from the Premier League.
Despite securing sponsorship in August 2007 and being run by the Charlton Community Trust, many of the players left and the club struggled to stabilise.
But over the last 16 years, Charlton have worked their way through the leagues, and were promoted to the then-named Women's Championship in 2018 after beating Blackburn in the FA Women's Premier League play-off final.
2021 also proved to be a landmark year. Charlton was bought back into the club's control from the community trust, and Karen Hills was appointed as manager.
That summer, the women's team went fully professional and have been working towards a place in the WSL ever since. In the last three seasons, Charlton have finished third, second and fourth, and should they win this weekend, will be their first appearance in England's top flight since 2008.
Battle of the experienced managers
While the play-off may be new ground for many, the managers in the dugouts come with a wealth of experience.
Rick Passmoor has coached in the women's game for nearly two decades, including spells with Leeds, Notts County and Lincoln. Before joining Leicester, he was assistant coach to Rehanne Skinner at West Ham.
He joined the Foxes on an interim basis on September 4 - three days before the opening game of the season against Manchester United after Amandine Miquel was sacked.
Passmoor was eventually appointed as permanent head coach, and spent much of the first half of the season hovering above Liverpool. But while the Reds' form improved, Leicester's did not, eventually finishing bottom of the table.
Karen Hills was part of the Charlton team that won the FA Cup in 2005, and returned to the club in 2021 with the aim of earning promotion to the WSL.
She has done so previously with Tottenham, guiding them into the top league in the 2018/19 season alongside co-head coach Juan Carlos Amoros. She spent 11 years at the club, guiding them amateur to professionals and eventually, a WSL club.
She is a manager who has been there and done it, and will need the same approach as she faces one of the biggest games of her career this weekend.