Corner to Chelsea. They've offered far more already in this second half than they did in the first.

Caroline Graham Hansen tries to do it all herself for Barcelona - and almost does!

The forward moves across the Chelsea box and eventually gets a shot away. Over the bar.

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More encouragement for Chelsea as Jessie Fleming finds space and looks to play in Guro Reiten.

The pass is slightly overhit but gaps are starting to appear, now it's just whether Chelsea can exploit them while keeping Barca out at the other end.

Yeah, thinking about it, that 'just' is doing a lot of heavy lifting.

Laura Bassett
Former England international on BBC Radio 5 Live

She's been starved of the ball the whole game and she seems like she's out of her rhythm. She looks like she doesn't know what to do with it.

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Better from Chelsea and they work the ball into Sam Kerr inside the box.

She tries to feed a ball in to Guro Reiten but the Norway international is on the deck. She thinks she was fouled but the replays show there was nothing in it.

Kerr might have been better trying to get a shot away in any case.

Patri Guijarro plays a lovely through ball to Asisat Oshoala. The striker's shot is blocked but that was a superb pass through the smallest of gaps.

Laura Bassett
Former England international on BBC Radio 5 Live

I think initially it was a fantastic tackle from Cuthbert. The goal and the opening opened up for Bonmati, but Cuthbert came out of nowhere. I just think there was no calmness about the defending because of where the ball was bouncing.

Fridolina Rolfo lets fly from 25 yards out. It's well struck with her left foot but the ball whistles just past the post.

Chelsea haven't got going yet since the break.

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Barcelona on the attack straight from kick-off. Aitana Bonamati has so much space to drive into before Erin Cuthbert gets across to make a challenge.

The ball breaks to Fridolina Rolfo on the left, she puts the ball into the middle and Chelsea make hard work of clearing it.

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We're back under way at the Nou Camp.

Lauren James was warming up at half-time. How long before she is introduced for Chelsea?

The visitors have done well to prevent Barcelona adding to their aggregate lead but they need a goal.

The players are back out. We're just about ready for the second half. No changes for each side just yet.

Vicki Sparks
BBC commentator, speaking on BBC Radio 5 Live

I think they an take encouragement from that first half. But as Laura and I were saying to each other at half-time, they've got to go for it.

Chelsea are doing their job very, very well at one end but at one point they have to win.

There were a few to choose from but Barcelona's best chance of the half fell to Mariona Caldentey after good work from Caroline Graham Hansen and Aitana Bonamati.

The Spain forward couldn't keep the shot down though. In fact, the only save Ann-Katrin Berger has had to make came from Bonmati's mishit cross - and even that may not have been going in.

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Emma Sanders
BBC Sport at Nou Camp

Chelsea's gameplan is working so far. They are trying to hold on for as long as possible then you would imagine they will take risks later on in search of that aggregate equaliser.

But Barcelona are giving them plenty of problems. Aitana Bonmati and Patri Guijarro are pulling strings, while Caroline Graham Hansen is really enjoying herself. Asisat Oshoala could have had a goal and Mariona Caldentey should have scored.

How long will Barcelona keep squandering their chances and when will Chelsea have to break the block to get that goal?

Emma Hayes' side have done well so far but they need to pull a rabbit out of the hat.

Laura Bassett
Former England international on BBC Radio 5 Live

I think Chelsea can be super happy with that first-half performance. You need to stay in the tie. If Barcelona has got a goal this crowd would have been behind them and it would have been wave after wave of attack.

I've been impressed with the way they haven't let Barcelona settle in those attacking positions.

A Barcelona free-kick beats everybody, goes out for a goal kick and that will do it for this first half.

The home side are ahead on aggregate and have been the dominant force in the opening 45 minutes.

Chelsea are still in it, though, and showed signs of promise at either end of the half.

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Emma Sanders
BBC Sport at Nou Camp

That was a huge chance for Jessie Fleming to test Sandra Panos and she miscontrolled it. Chelsea might only get one or two of those chances and they HAVE to take them. She immediately apologised to Sam Kerr and Emma Hayes had to disguise a frustrated spin in the dugout.

Chance for Chelsea. They win the ball back well and get in down the right. Niamh Charles is in acres of space but Sam Kerr doesn't spot her.

Instead she plays the ball to Jessie Fleming but a loose touch allows Barcelona to scramble it clear.

The offside flag then goes up so it may all have been academic in any case.

Into the last minute of the half and for all Barcelona's possession and the chances they've created, they've yet to have a shot on target.

Chelsea are still waiting for their first shot of any variety.

We're have three minutes of added time.

Laura Bassett
Former England international on BBC Radio 5 Live

That's how they dominate the La Liga, they rotate a lot as well. That's how easy they find it and when they do come to the Champions League they have to find another gear, another level.