Fran Kirby gets in behind the Wolfsburg defence down the right channel after a good ball forward from Millie Bright.

But the forward clips the ball towards goal and it goes well wide.

With support coming into the box, she seemed to be in two minds whether to shoot or cross. In the end, it was neither.

The final ball has been letting down the Blues.

Katie Chapman goes close with a header from Magdalena Eriksson's left-wing corner, but can't get her effort on target.

Ewa Pajor drives at the Chelsea defence after an error from Maren Mjelde, but her effort is blocked behind for a corner by Magdalena Eriksson.

Hedvig Lindahl holds onto the delivery from the right and looks to get the Blues going again.

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We've just seen a brilliant challenge from Nilla Fischer on Eniola Aluko.

The Wolfsburg captain slides in to turn the ball behind for a corner. If she had got that wrong it would have been a penalty.

Home keeper Almuth Schult claims the ball well from the corner.

Almost an opening for Chelsea!

After great interplay from Fran Kirby and Ramona Bachmann, the final ball is lacking looking for Hannah Blundell.

In the end the ball falls to Eniola Aluko, but her half-volley curls well away from goal.

Hannah Blundell and Ramona Bachmann combine well looking to get Chelsea on the front foot, but Fran Kirby has to check back and Wolfsburg defenders flood back to win back possession.

Chelsea Ladies are top of Women's Super League One, but are finding the German side a tougher nut to crack.

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Sue Smith
Former England forward on BBC Sport

Sara Bjork Gunnarsdottir's runs into the box, considering she's a holding midfielder, is why she gets goals because of how well timed they are.

She's got players around her who can pick her out and see the pass.

Chelsea captain Katie Chapman picks up a caution for a body-check on Pernille Harder on halfway.

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Wolfsburg create another opening, and Chelsea are under pressure.

Ewa Pajor clips a ball across the box looking for Sara Bjork Gunnarsdottir, but the midfielder can't quite get to the ball in time and glances a header well wide.

Wolfsburg left-back Noelle Maritz goes into the book for pulling Ramona Bachmann over on the right flank.

Chelsea win their first corner after good work from Eniola Aluko on the right hand side.

The delivery is too the edge of the box from Ramona Bachmann and Wolfsburg clear.

Millie Bright decides to try her luck from all of 35 yards out, and her speculative shot is well over the bar.

But, encouraging signs for the visitors.

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Referee Olga Zadinova plays a good advantage as Katie Chapman crunches into a Wolfsburg player just outside the box.

The ball breaks to Lara Dickenmann on the left, who flashes a cross into the six yard box.

However, it rebounds behind off a team-mate.

Anna Blasse is fouled midway inside the Chelsea half, offering the home side a chance to work a set piece.

They take it quickly down the right, but the cross is overhit - which is a let-off for the Blues.

Chelsea Ladies boss Emma Hayes, who is pregnant with twins, has been shouting some advice to her team from the sidelines.

Chelsea look organised defensively so far and have done well to repel the hosts' advances

But the Blues need goals and are yet to properly test Wolfsburg keeper Almuth Schult.

Chelsea Ladies striker Fran Kirby gets on the ball for the first time and drives at the defence.

As she approaches the box she looks for a one-two with Ramona Bachmann but the return ball from the Switzerland international is wayward.

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Lena Goessling volleys an effort from the edge of the area after Chelsea fail to clear a corner properly, but it deflects off a teammate and straight into the arms of Hedvig Lindahl.

Chelsea work an opening on the left for Ramona Bachmann after a good team move.

The ball breaks to Ji, but the South Korean's ball looking for Fran Kirby is under-hit, and the hosts scramble the ball clear.

A crucial save from Hedvig Lindahl to keep Chelsea in the game.

She is quick to come off her line and smother a shot from Caroline Hansen, who had been played in by a cracking through ball from Pernille Harder which was threaded through the defence.

Wolfsburg have won this competition twice, in 2013 and 2014, and are on course for a domestic double.

Chelsea are top of Women's Super League One but this is their first European semi-final.

The Blues have settled well but will need to take their chances if they are to overturn that 3-1 aggregate scoreline.

Ramona Bachmann is muscled off the ball by Wolfsburg captain Nilla Fischer close to the byline.

Sue Smith
Former England forward on BBC Sport

That's what Chelsea have to be careful about. It's Wolfsburg's quick counter attack. Pernille Harder makes those late runs into the box which are difficult to pick up.

Chelsea need to be aware of what Wolfsburg can do on the counter.