The final Women’s Super League One season before the autumn rebrand and restructure draws to a close this weekend. On Tuesday night, Chelsea will be crowned champions with one game to play if they avoid defeat at Bristol City. That is not a conclusion everyone had seen coming.

At the end of January the top tier looked very much like the men’s Premier League. Manchester City were dominant, having won all seven league games and 17 in a row across three competitions. Although Chelsea had dropped two points, it felt as though the title was City’s to lose.

Since then, however, Nick Cushing’s City side have picked up 11 points from a possible 27, fewer than Birmingham, Chelsea, Reading, Arsenal and sixth-placed Liverpool. They lost the League Cup final against Arsenal and, whereas Chelsea remain unbeaten in the league, City have lost four games, crumbling at the business end – three of those coming in their past five matches.

Now, with two games to play, they sit six points below Emma Hayes’s Chelsea. So where did it go wrong?

It is fairly simple. Whereas Chelsea have built a deep and experienced squad capable of competing on all fronts, City have not. Both sides have lost players to injury, some long-term, yet Hayes has still been able to rotate and has always had someone capable of stepping into the breach – most notably Maren Mjelde moving into the back four from midfield with ease.

Whereas the average age of defenders used by Chelsea is 26, City’s is 24. The midfield average age gap is even bigger, Chelsea’s 27 to City’s 24. City’s team is young and their squad is younger.

So while Chelsea have been able to rely on experience in their backline (players range from 24 to 33 outside their most-used back-four) City have had the talented but less experienced Mie Jans, 24, Megan Campbell, 24, and Esme Morgan, 17, to fall back on. Chelsea’s more experienced regular defence have this season played 13 fewer games between them than City’s over-relied-on back four of Jen Beattie, Abbie McManus, Demi Stokes and Steph Houghton.

In midfield the problem is the same: four Chelsea players have played fewer than 28 games this season (only the veteran Katie Chapman reached 29) as Hayes has rotated to deal with the fixture pile-up caused by the team’s progress in two domestic cups and to the Champions League semis. At City, three midfielders have played more than 28 games, with 21-year-old Kiera Walsh playing 34 across all competitions. No wonder City players have started to show signs of fatigue.

Both sides have a wealth of attacking talent but City have lacked a real goalscorer. Fran Kirby has 25 goals for Chelsea as part of a potent frontline, all of whom have chipped in. But City have not had a stand-out player up front. They brought in German forward Pauline Bremer from Lyon in exchange for arguably the world’s best right-back, Lucy Bronze, in the summer, but three games in, and after she had scored her first goal, Bremer suffered a horrific leg break.

Manchester City’s Izzy Christiansen. Photograph: TGSPhoto/Rex/Shutterstock

As the margins City were winning by began to shrink, Cushing turned to the Portland Thorns and Denmark forward Nadia Nadim in the January transfer window. After scoring six minutes into her debut against Reading, then the winner in City’s Continental Cup semi against Chelsea, she looked to have settled in well. But she trailed off disappointingly, making six starts and scoring two goals in 14 appearances. City allowed Toni Duggan to leave for Barcelona in the summer and with the striker finishing as Barça’s top scorer, with 14 goals in all competitions, their failure to recruit suitable back-up or to deepen the squad seems to have been costly.

Chelsea won the FA Cup final this month and if they wrap up the double on Tuesday, or at Liverpool on Sunday, they will be worthy winners. Their exciting, interchangeable attack has been anchored by a rock-solid defence, and City have struggled to play with as much verve.

Even if Chelsea seal the title on Tuesday there will be much to play for behind them. The restructure of the pyramid means there will be no relegation but at the top end three points separate second and fifth. If City continue their slide they run the risk of finishing without a trophy and outside the two Champions League places, with Arsenal on their heels and Reading still with an outside chance.

Anyone pining for football now the Premier League season has finished could do a lot worse than watching a gripping WSL1 term reach its conclusion.

Talking points

• Doncaster Rovers Belles won Women’s Super League Two after Durham put four past title-chasing Brighton. Belles celebrated with a win against third-place Millwall, Jade Pennock’s strike taking a heavy deflection to inflict Millwall’s first home defeat since February 2017. Belles’ striker Jessica Sigsworth is on course to finish as WSL2’s top scorer; she has 11 goals, one more than team-mate Kirsty Hanson and Durham’s Beth Hepple with a game to play.

Doncaster Rovers Belles celebrate after winning WSL2. Photograph: Balint Hamvas for FA/Rex/Shutterstock

• Lyon secured the Division 1 Féminine title for a record 16th time and 12th in a row. They sealed the title without dropping a point, scoring 98 goals and conceding five, a 7-0 win against Marseille pulling them out of reach of Paris St-Germain. Lyon face PSG in their final game before travelling to Kiev to play Wolfsburg in the Champions League final as they aim for another treble.

• Atlético Madrid saw off Barcelona to retain their La Liga Iberdrola title by one point. Atlético beat Zaragoza 6-1 on the final day while Barcelona put five past Levante. Barcelona, having recruited hard, including Toni Duggan from Manchester City and the Euro 2017 winner Lieke Martens, were favourites to pip Atlético to top spot. Atleti have announced the signing of this season’s top scorer Charlyn Corral from Levante.

• New Zealand Football and the NZ Professional Footballers’ Association have negotiated a new collective bargaining agreement that gives the women’s national team equal pay, equal prize money, equal rights for image use and, crucially, travel parity when representing the country.