Entering the final minute of the 90, it looked as though our defence of a trophy we won for the first time last February was going to come to an end against a club that has long tormented us in this competition.

Despite taking the lead on the stroke of half-time through Melanie Leupolz, who made the most of a defensive slip-up to smash home a half-volley from Erin Cuthbert’s free-kick, we hadn’t taken advantage of the chances that had come our way earlier in the half, most notably through Bethany England and Sam Kerr.

City drew level shortly after the interval when a mix-up between Ann-Katrin Berger and Magdalena Eriksson allowed Chloe Kelly to fire in the equaliser, a goal which came completely against the run of play, and they looked to have stolen it when Lauren Hemp netted inside the final 10 minutes.

However, there was a twist to come in the closing moments of normal time, as substitute Niamh Charles netted a sublime equaliser, taking a pass by Guro Reiten on her chest and unleashing a looping volley that flew into the top corner and sent the tie into extra time.

Our Norwegian schemer went from provider to goalscorer early in the additional 30, as she got on the end of a Pernille Harder cross to steer it home at the back stick, and then, on the stroke of half-time, came the clincher – and what a show-stopper it was.

Reiten kept her cool on the edge of a crowded penalty box to roll the ball back to Sophie Ingle, who hit a blockbuster strike with her left foot that beat the despairing dive of the keeper and sparked jubilant celebrations on the pitch and on the sidelines. Three goals had been scored in the space of 15 minutes, each of them by substitutes, to turn this tie on its head.

The Academy Stadium has never been a happy hunting ground for us and City’s previous three meetings with us in the competition, each of them at the semi-final stage, had all ended in defeat. That the Blues were able to turn this around when facing a fourth loss to them speaks volumes about the mental strength of this squad.

We’ve now beaten our rivals three times in three different competitions this term, and attention will turn back to the WSL and a trip to Bristol City on Sunday, when we can set a new record for the longest unbeaten run in the history of the competition if we avoid defeat.

Before then, we’ll discover our opponents in the last four of the competition, when Durham face West Ham tomorrow night. The winners will travel to Kingsmeadow in the first midweek in February.

After a hard-fought win over the other top Manchester club in the WSL last Sunday, Hayes opted to make only one change to her starting XI, as she restored England to the line-up in place of Fran Kirby, five years to the day since our No9 signed for the club.

An attacking quartet of England, Harder, Cuthbert and Sam Kerr were offered ample support from midfield by Leupolz and Ji So-Yun. Behind them was the most miserly back five in the country, as Berger retained her place in goal, protected by a back four of Maren Mjelde, Millie Bright, Eriksson and Jonna Andersson.

Storm Christoph was out in full force at City’s Academy Stadium, as the rain fell by the bucketload from the first whistle, but it didn’t seem to hamper either side, as the slick surface allowed the ball to zip through that little bit quicker.

Chelsea certainly seemed to adapt to this first, as we carved through the home side’s defence twice in the first 10 minutes. England was only half a yard away from getting on the end of an inviting cross by Cuthbert, who had performed so impressively in our last game against City to keep Lucy Bronze quiet, and then Kerr shot into the side-netting with only Karen Bardsley to beat.

Ji was slowly beginning to exert her influence on the game from deep, pinging a couple of through-balls over the top that weren’t far off their target, but the first quarter of this contest passed by with both teams showing each other plenty of respect by not overcommitting in the attacking third.

The Blues bench were calling for a penalty when Cuthbert appeared to have her heels clipped inside the box, but the Scot made little fuss and quickly dusted herself off to regain possession and then try her luck with a thumping drive from distance that didn’t miss the target by much.

Our Scottish attacking midfielder was at the heart of our best attacking moves throughout the first half, so it was only fitting that she was involved when the deadlock was broken on the stroke of the interval. In truth, her free-kick from out wide should have been cleared by Alex Greenwood, but the England international’s miscue allowed Leupolz to take aim and fire in a thunderous half-volley that beat Bardsley to put us in front.

It was our No8’s third goal for the Blues and first since she netted from the penalty spot in our most recent Continental League Cup game, which was against Tottenham Hotspur at the start of November. Unsurprisingly, it was also enough to ensure we went into the break with a deserved lead.

Having struggled to cope with our impressive midfield, the home side opted to call on a former Blue in a bid to take control in the middle of the park, as Laura Coombs was introduced in place of Keira Walsh. Within seven minutes of the restart, they were level.

The substitution had little bearing on the goal, however, as we were responsible for our own downfall. Berger’s quick throw to Eriksson immediately put her under pressure, facing her own goal, and the skipper's attempted clearance hit straight into Kelly. The City winger didn’t need a second invitation to fire past Berger from close range.

Up to that point, Berger had been a virtual spectator, only called upon to mop up behind the back four, but at the other end her opposite number Bardsley was being kept on her toes and she was called upon to make a fine save to tip Harder’s low strike around the post.

A few minutes later, Hayes made her first substitution when she brought on Reiten in place of Cuthbert. It almost paid dividends immediately, as an outswinging corner by the Norwegian was met by a firm header by England that landed on top of the net.

Chelsea continued to look the more threatening side, as we had throughout the contest, but we were often met with a wall of sky blue shirts, blocking the path to Bardsley’s goal. It wasn’t all one-way traffic, however, as City showed with a lightning-quick counter that ended with Hemp only just missing out on taking full advantage of a teasing cross from Kelly.

A double-substitution followed for the Blues, as Ingle and Charles came on for Ji and Kerr, but we soon found ourselves trailing as a corner wasn’t properly cleared and Hemp was able to force the ball past Berger with a left-footed strike.

But this side simply does not know when it’s beaten, and an incredible piece of skill from Charles drew us level in the final minute of normal time. This time it was City failing to deal with a set-piece, but when Reiten clipped a cute pass over the top for her fellow substitute there appeared to be little on. Charles had other ideas, controlling it sublimely on her chest and then looping a spectacular volley over the despairing dive of Bardsley. A breath-taking strike from a player who certainly has a bright future in the game.

Charles’s magic moment ensured a contest that became more engrossing the longer it went on would have an additional 30 minutes for both sides to try to find a winner. Only five of those extra minutes were required for the Blues to regain the lead, and it was another substitute who found the back of the net. This time it was Reiten who was at the back stick to get on the end of a cross that Harder fizzed across the six-yard box, sliding in to send a shot slowly trickling into the far corner as time seemed to stand still.

City almost hit back immediately, as Stanway went through on goal and forced a fine save from Berger, who showed bravery and no small amount of skill to keep us in front. Our reward came a few minutes later at the other end, as Ingle scored a goal to rival Charles’s to put the game out of sight.

Reiten kept her cool on the edge of the box as the ball pinged about, rolling it invitingly into the path of Ingle to run onto and hammer an unstoppable strike with her left foot that flew into the top corner. What a hit! Our Welsh midfielder might not score many but, as she proved last season with her Puskas-nominated effort against Arsenal, when she does they tend to be pretty special.

The goal seemed to knock the stuffing out of City, who had given it their all and now found themselves needing two goals in the final 15 minutes just to take it to penalties. It was never going to happen, and we comfortably held them at bay to seal a famous win that keeps our run going in this competition.

The Blues are next in action on Sunday, when we travel to Bristol City on Sunday for a chance to maintain our place atop the league table and to make WSL history with the longest unbeaten run, having equalled the record last weekend.

Man City (4-3-3) Bardsley; Bronze, Houghton (c), Greenwood (Beckie 59), Morgan; Walsh (Coombs h/t), Scott, Stanway; Hemp, Kelly, White (Park 105)Unused subs Roebuck, Ravening, Phillips, Davies, WindowScorers Kelly 52, Hemp 85

Chelsea (4-2-3-1) Berger; Mjelde, Bright, Eriksson (c), Andersson; Ji (Ingle 83), Leupolz; Harder, England (J Fleming 105), Cuthbert (Reiten 62); Kerr (Charles 83)Unused subs Telford, Blundell, Spence, KirbyScorers Leupolz 44, Charles 90, Reiten 95, Ingle 104

Referee Richie Watkins