​The Women’s Super League returned this weekend and with it a host of new signings, improved squads and unexpected results.Manchester City began the defence of their title with victory at home to newly-promoted Birmingham City, while underdogs Crystal Palace upset Everton.But which clubs made a statement and do Manchester City look like title favourites again? Find interviews and extra content on the BBC Women’s Football Weekly feedMixed bag from WSL title rivalsAs is the case with any new season, an early look at title challengers does not give the whole story but can be a good marker of who has the right credentials.There were debuts for big-name signings Ona Batlle and Georgia Stanway at Arsenal, while Katie McCabe swapped red for blue when she started for Chelsea.Manchester City also had new faces off the bench as they navigated an injury-hit squad on opening weekend.But the reigning champions could not have hoped for a better start as they hosted WSL 2 winners Birmingham at the Joie Stadium and cruised to a 3-1 victory.It was an assured display, full of the attacking flair and threat they unleashed last season with the only criticism that they should have scored more.Birmingham City were no pushovers and performed well on their return to the top flight, but Andree Jeglertz’s side still imposed their superiority.The Swedish boss was delighted with victory, though the perfectionist in him wanted more after a “hesitant” first half.”In the first half, it was almost [like we were] getting into it again. We turned it around and the second half was much smoother,” said Jeglertz.”It’s about driving the game and we did that. Even though we scored goals, we wanted more.”New season, same flaw – Chelsea title hopes already under scrutinyManchester City did what Chelsea could not as Sonia Bompastor’s side were held to a frustrating 1-1 draw by Aston Villa at Stamford Bridge. Despite 57 touches in the opposition box, 23 shots inside the area, an effort that hit the crossbar and a disallowed goal for offside, Chelsea could not break Villa down.Their lack of ruthlessness was a consistent characteristic last season as Chelsea, who had won the previous six WSL titles, fell to third in the table.Their opening display did little to ease concerns it would be a similar story this season, while City showed they remain a serious force to overcome.Elsewhere, the bookies’ favourites to win the league, Arsenal, did not find life easy at Brighton for their opening game. Arturo Ruiz, 29, took charge of his first match for Albion – a side many think can challenge the WSL’s giants – and they made life tough for the Gunners.A moment of quality from 19-year-old Lisa Baum on her Arsenal debut won the points in a 1-0 victory and, while unconvincing, it remains early days.Emerging challengers show upLast season’s Champions League quarter-finalists Manchester United did not get off to a good start under manager Eva Olid as they were beaten by a surprisingly fluid display fro