The 45-year-old has led Chelsea to 11 trophies, including back-to-back WSL titles in the last two seasons, and a Champions League final appearance.

When Hayes joined Chelsea in 2012 they had finished sixth in successive seasons. A year later they finished seventh but in each campaign since, bar a third-place finish in 2019, they have ended in the top two.

• WSL Fixtures | Table | Live on Sky Sports | Get Sky Sports
• WSL: Chelsea face West Ham, Man Utd vs Everton live on Sky Sports

Unsurprisingly, they are in contention for a third consecutive WSL title this campaign - but it's been a long road to where they are now.

"When she went in, she didn't have many resources to give her and Chelsea the platform to perform at the levels they're performing at now," said Sky Sports' lead WSL pundit Karen Carney told the Women's Super League Special on Tuesday evening, from 6pm.

"They had a £60,000 budget for the whole season and what she's got now is a massive team behind her, scouting, analysis, which gives her the ability to go and compete."

Chelsea won the WSL, FA Cup, League Cup and Community Shield last season before being beaten in the Champions League final by a superb Barcelona side.

One key component to their success, Carney believes, comes from their recruitment although to reach that stage, Hayes has had to convince the club to supply her with more resources. In turn, that has changed the way the rest of the WSL operates.

"In football, especially in the women's game, we can look at just specifically what we see," said Carney, "but I think a lot of the teams, not just Emma Hayes' Chelsea, are really recruiting well to give them the right platform to perform, and you need staff and investment.

"That's what she's done. She's gone in and demanded. Training grounds, the majority, if not all of them, are now training at the best facilities. She went into Chelsea and demanded that, and it's snowballed on to all the other teams."

How Chelsea have changed their style from last season

Chelsea, unsurprisingly, are in the title hunt once again this season. They trail leaders Arsenal by eight points, having been held to a 0-0 draw by the Gunners last month, but have three games in hand to cut the gap.

Hayes's side have conceded just six goals in their 13 league games and despite their unprecedented success of last season, they have changed their style of play.

"She's constantly evolving," said Carney. "This season they've been a 3-4-3, evolving from a four [at the back] and pushing more players forward.

"They're attacking with more width, their possession has been a lot better, they're giving the ball away seven times less per game. That might not seem a lot but when margins are so small those errors can really count for many things and lose you points.

"Their style has changed, and they've had to change that because when you're the champions team defend differently. They want to stop you differently. They've had to evolve and learn how to beat these low blocks."

Chelsea's dangerous front three can click

Chelsea's new style allows for Fran Kirby, Sam Kerr and Pernille Harder to play in an exciting front three together.

Although Harder's numbers are down from this time last season, the prospect of the trio in this system, with more time to gel, could become a fierce force.

"On paper, they're the perfect mix," said Carney. "Looking at Fran Kirby and Sam Kerr, there clearly seems to be a connection between them, looking at the stats, Pernille is slightly behind in that.

"She's actually better when she plays on her own, she creates her own stuff. If the three of them can play more regularly together, I don't think they've had too many games together, maybe three, and build those connections.

"Pernille is at her best when she is running and spaces appear for her. I think she's better from the wider areas or in a number nine position. When I watch her I think she's better without Kerr and Kirby when she can be route one and direct. If they can get them all connecting a bit more the league will be watching out."

Watch the Women's Super League Special on Sky Sports Premier League and Sky Sports Football at 6pm.