A penalty shoot-out looked almost certain as a thrilling match edged to a conclusion, but the Blues substitute popped up with a dramatic winner to send Wheatsheaf Park into ecstasy.

That we even had extra-time at all owed much to a stunning free-kick from Ji So-Yun in the dying minutes of the 90, equalising a scrappy goal by City's Jane Ross.

The Blues were back in action for the first time since a 6-0 win over Aston Villa a fortnight ago in the previous round of the FA Women's Cup and Emma Hayes was able to call upon Claire Rafferty at left-back after injury. However, Niamh Fahey was absent at centre-half through injury, which meant Millie Bright continued alongside Gilly Flaherty, with Hannah Blundell at right-back. Hedvig Lindahl returned between the sticks in place of Becky Spencer.

In midfield, Jade Bailey and Katie Chapman lined up behind the attacking trio of Gemma Davison, Ji So-Yun and Karen Carney, with Eniola Aluko named as the lone centre-forward in place of Fran Kirby.

The pace of the Blues No9 was proving to be a useful outlet in the early exchanges between the two sides, which were as cagey as one might expect from an FA Women's Cup semi-final and with a place at Wembley up for grabs.

In fact, there was little goalmouth action to mention, save for both goalkeepers confidently claiming crosses, from the opening 20 minutes of the match. Set-pieces were looking the most likely route to goal for the visitors and one such opportunity saw Lindahl save bravely at the feet of a City forward and then Asllani fired the rebound just wide of the target.

That led to a response from the Blues, who began to keep possession in the attacking third and a chance finally fell to Blundell as the ball popped up nicely for the right-back to try her luck with a dipping half-volley which wasn't too far wide.

A fierce midfield battle was playing out throughout the first half, resulting in our skipper going into the referee's notebook for one foul too many, and she was soon to be joined by Carney, who also had our first shot on target with a long-range effort which Karen Bardsley claimed.

The best strike of the half came with just five minutes remaining and it was from the boot of City's captain Steph Houghton, who lined up a free-kick in a threatening position and curled an effort which looked destined for the top corner until Lindahl brilliantly clawed it away at full stretch.

There were no changes made by either side at the half-time interval, but there was certainly a change in approach as both teams looked to get on the front foot.

City enjoyed the better of the opening minutes of the second period and when Duggan headed wide with a free header, it didn't take long for Hayes to shuffle her pack as she replaced Bailey with Drew Spence.

Chelsea's best chance of the game came just after the hour when Blundell brilliantly jinked her way down the right and stood up a cross at the back post for Carney to attack. Her header looked to be goal-bound but Bronze managed to get her head in the way to deflect it wide.

Suddenly the Blues were finding a bit more joy down the flanks, but City remained a threat on the counter and on one such occasion it took a perfectly timed challenge from Flaherty to keep out Parris. The centre-back was then crudely taken out by Bronze, who became the first player from the visiting side to be cautioned.

City threatened again in the 70th minute when a low corner-kick was flicked towards goal by Duggan, but Lindahl judged her angles to perfection and watched it past the post. At the other end, Davison was next to try her luck for the Blues, intercepting the ball in midfield and running at her marker before shooting straight at Bardsley.

The deadlock was finally broken in the 72nd minute, but it wasn't the way the majority in Wheatsheaf Park had hoped. Another set-piece from the visitors caused mayhem in the Chelsea box and although Duggan couldn't beat Lindahl, Ross was on hand to turn home the rebound.

Hayes brought on Kirby and England in a bid to get the equaliser and the change paid off when the latter was fouled just outside the penalty area, giving Ji a great opportunity with a free-kick. Her effort was simply sublime, clipped over the wall and swerving into the far corner – it was in from the moment it left her boot.

Buoyed by the goal, the Blues dominated the closing stages of the 90 minutes but were unable to call Bardsley into action and so the game finished 1-1 and a period of 30 minutes' extra-time followed.

The first half of extra-time produced plenty of attacking endeavour from the home side but few clear-cut chances. However, an opening was manufactured thanks to some excellent link-up play from two of our forwards. Aluko played in Kirby, who held the ball up and waited for her team-mate to catch up before sliding in the return pass, but the Blues No9 could only send a low shot straight at the keeper.

Chelsea almost made a perfect start to the second period of the added 30 minutes when Gemma Davison broke clear down the right and squared for Kirby, whose touch was excellent only for the finish to sail harmlessly into the arms of Bardsley. Davison went even closer with our next chance, despite being confronted by two defenders and a tight angle, but her low drive flew inches past the far post.

It wasn't all Chelsea in extra-time, though, and City almost snatched it at the death when a corner was floated in the direction of Jill Scott, whose header almost slipped under Lindahl. Then, up the other end, the Blues won it with virtually the last kick of the game. Kirby was played through on goal and the substitute kept her head to send a low finish past Bardsley. Wheatsheaf Park erupted – what a stunning conclusion to a thrilling match.

Whatever will be will be, we're going back to Wembley!

Chelsea (4-2-3-1): Lindahl; Blundell, Bright, Flaherty, C Rafferty (England 82); Chapman (c), Bailey (Spence 53); Davison, Ji, Carney (Kirby 75), Aluko

Unused subs: Spencer, Borges

Goals: Ji 86, Kirby 120

Booked: Chapman, Carney

Manchester City (4-3-3): Bardsley; Bronze, Houghton (c), McManus, Stokes; Scott, Corboz (Beattie 90), Asllani; Parris, Ross, Duggan (Stanway 86)

Unused subs: Hourihan, Tynan, Paul

Goal: Ross 72

Booked: Bronze

Crowd: 2,278

The final will be against Arsenal Ladies on Saturday 14 May, kick-off 2pm. Ticket details for Chelsea fans will be announced as soon as we get it.