To mark the anniversary, we recall that day and also recount the story of how match-winner Ji became a Chelsea player....

In front of over 30,000 supporters at Wembley Stadium, our South Korean midfielder Ji settled the showpiece final, just as she had done in the semi-final win against Manchester City.

The opener came on 37 minutes when Eniola Aluko advanced into the box to find Ji. The No.10 kept her composure under pressure and finished from close range against her now team-mate Carly Telford.

Our South Korean star, who was voted by her peers as the PFA Women’s Player of the Year in 2015, helped make club history and here we recall the incredible story of how she became a Blue…

It’s 5.30am when the alarm on Emma Hayes’ phone goes off, a wake-up call that is as unwelcome as it is essential. The previous night the Chelsea Women boss had been in a dingy Tokyo karaoke bar, singing and dancing as if she didn’t have a care in the world. Now she has to get herself ready before heading down to the lobby of the hotel where she and the Blues squad have been based during a once-in-a-lifetime trip to Japan and set the wheels in motion for arguably the most important transfer in the history of Chelsea Women.

To the uninitiated, the timeline of Chelsea’s signing of Ji So-Yun seemed pretty straightforward. Sunday 8 December, 2013: the Blues are played off the park by INAC Kobe Leonessa in the final of the International Women’s Club Championship in Tokyo, with Ji, who had been labelled the Korean Messi, head and shoulders above every other player on the pitch. Tuesday 28 January: Ji is in the stands at Stamford Bridge alongside a beaming Hayes, clutching a Chelsea shirt with her name and the No.10 on the back.

Sometimes transfers really are that simple, but not this one. Well, at least not as far as Hayes’ interest goes. It was in 2010, two years before she took on her first managerial position in England here at Chelsea, that she first set eyes on Ji and knew this was a player she had to work with one day. During a commentary stint for Eurosport on the Under-20 Women’s World Cup, Hayes spotted a precocious No.10 playing for a South Korea side which, against the odds, went deep into the tournament, eventually finishing third. Ji scored a hat-trick in their opening victory against Switzerland and was on target in all but one game of their campaign, earning her the Silver Ball as the second best player of the tournament.

“More than anything, I remember watching her and thinking this is a player who knows which pass to make, where to stand at the right time, someone who seems to make the right decisions all the time,” says Hayes, taking up the story. “And her execution was at such a high level for someone so young.

“In women’s football, Asian countries produce unbelievable No.10s, because they are nations who aren’t obsessed with size and physicality. You’ve got America, Germany, the top powerhouses in women’s football – it’s all about power and physical prowess and pace. In Asia, it’s the opposite – it’s about technique and decision making. In the women’s game, the diminutive No.10s, the ones who get the comparisons with players in the men’s game, come from Asia.”

The teenager from Seoul was already a regular at senior international level, having made her debuted for her country at the age of 15, and soon after the Under-20 World Cup she left her homeland to join Japan’s leading side, INAC.

As fate would have it, Hayes and Ji would soon be crossing paths for the first time. During her stint as technical director of Sky Blue FC, a New Jersey-based side, a tour of Japan was arranged at the tail-end of 2011.

“INAC were one of our opponents and we actually played them in two different cities,” recalls Hayes.

“Ji was playing for them and we actually trained with INAC, great sessions where the two teams were mixed. At the end of our trip, INAC asked if they could sign any of our players.

"The league was on the verge of folding in the US, which it did soon after, so I suggested Rebecca Moros and BevGoebel-Yanez. They both ended up staying a couple of years.”

Fast forward to the end of 2013 and Hayes had taken the reins at Chelsea Women and, by all accounts, things weren’t going quite as either party hoped. There was some cause for optimism, though, when a call came through from the organisers of the International Women’s Club Championship, looking for a last-minute replacement after Arsenal had pulled out.

But how on earth was a club that had just finished second from bottom in the Women’s Super League, with only three league wins all season, going to attract a player who had the world at her feet and could potentially transform our fortunes?

“The work that went into signing Ji was immense,” adds Hayes. “It required so much – but, as much as anything, we were in the right place at the right time. When had Chelsea Women ever been to Japan?!

“I went out with Bev and Becca when we were over there and I said to them, ‘Please,you’ve got to help me with this player…’ Ji could play for any club in the world, I’ve said thatsince day one. But the rest of the world didn’t know how to get to Ji.

“Through my own network, I was able to get a character reference, if you like, across to her that I was a good person and I would look after her. I think that had a massive impact. Having conversations with agents is not difficult. But now, knowing Ji like I do, I can totally understand how that was valuable to her. My relationship with Ji is extremelymaternal; I feel huge responsibility for her, being so far from home, and English not being her first language. She’s a real mummy’s girl, real home bird – but a top pro who has given unbelievable things to Chelsea.”

Before a ball was even kicked in the IWCC, a story emerged in the Japanese media that Ji was interested in moving to the Women’s Super League. Her preferred destination wasnot Arsenal, the traditional powerhouse of English football, but Chelsea.A meeting with Ji’s agent was hastily arranged but there was no common language between him and the Chelsea committee, led by Hayes and her assistant, Paul Green.

“It was hilarious,” says Hayes, guffawing at the memory. “Let me tell you, there were a lot of different facial expressions and hand gestures being used to get points across by both sides.

And a lot of laughter! I think trust was established at that point, though, and trust was absolutely at the heart of the deal.”

Of course, there was also the small matter of a football tournament to try and win. The Blues may have been a long way from the current set-up, which has won a steady stream of silverware over the past five years, but a largely part-time squad overcame a decent Sydney team in the semi-finals in Japan.

Laura Coombs, Eniola Aluko and local hero Yuki Ogimi were on target in a 3-2 victory for Chelsea against a side who boasted Sam Kerr among their ranks. With INAC unsurprisingly brushing aside Chilean side Colo Colo in the other last-four tie, we would come face to face with Ji a few days later. And the South Korean didn’t disappoint.

“It was like when Barcelona played Manchester United in that Champions League final at Wembley – and Ji was the star,” is Hayes’ assessment of a 4-2 defeat for the Blues in which Ji scored once and ran the show. “She was just unbelievable. After about five minutes I turned to Paul and Stuart [Searle] and said, ‘She is ridiculous.’

“I knew it was going to be a long afternoon. There was a gulf between the two teams, one of which had been together a long time and the other was just being put together. But it was a great trip, a real starting point for the journey for us.”

A strong connection was built up between squad and staff during a series of team-bonding exercises, including a highly competitive visit to a bowling alley, but with the football over and done with and the flight home set for early the following morning, there was only one thing for it. The last night had to be a biggie.

After visiting a local Korean barbecue, attention soon turned to the next stop. While this was being planned, however, a call came in from Ji’s agent wanting to meet one last time before they flew back to England. A 6am liaison was committed to by both parties, but there was no way they could bail on the squad before the night had even got started.

Next stop: a karaoke bar. There was an eyecatching performance of Oasis’ underrated gem Slide Away by Green, but the assistant manager was upstaged by an unlikely duet between Hayes and midfielder Coombs. “We did Ice, Ice Baby,” says Hayes, and that’s enough to set her off again with that infectious laugh.

“I am so, so grateful none of that wascaught on video. We had so much fun that night! Then the next morning we were sat in the lobby, having a coffee with the agent, trying to string out sentences in broken English for him to understand. It was surreal.”

Although the meeting seemingly went well, neither Hayes nor Green felt confident the deal would go through. It all seemed too good to be true. However, not long after that meeting, a deal was agreed and the necessary contracts were signed. Ji was a Chelsea Women player.

“And the rest is history,” adds Hayes. “In the women’s game, to put it bluntly, no one knew who she was. She was a secret world star and because we didn’t have the publicity… if it was in the men’s game, Ji would have been one of the top players in the world then. She is now.

“You don’t find a player like her all the time. She’s unbelievably special. She put a lot of faith in the club, and we have in her – but she had to take the bigger leap in faith, joining a club which looked very different to how it does now. She trusted me when I said I was going to build the team into one of the best in Europe. I kept saying, ‘Give me time to do that, trust me.’ She did, and I’m so grateful for that.”

Within a year of her arrival, Chelsea were title challengers and soon to become serial trophy winners, with Ji netting the winner in the maiden Women’s FA Cup final played at Wembley Stadium as the Blues lifted major silverware for the first time. She was also named PFA Women’s Player of the Year in that same season, 2015, and has since gone on to establish herself as one of the top midfielders in both England and Europe.

Sometimes the best things in life are worth waiting for…

This article first appeared in the club's monthly magazine.