Barca pressing, but the final ball isn't there. Sociedad getting so deep that they'll soon be defending on the goalline. Barca corner, attack snuffed out.

Ryan Crombleholme:, external Nou Camp is wonderful, amazing atmosphere but nothing beats Bayern's Allianz Arena.

It's not just England and Spain, there have been cup games across Europe tonight.

Lyon will play Paris St-Germain in the French League Cup final after beating second tier Troyes 2-1.

And Roma lead Napoli 3-2 following the first leg of their Italian Cup semi-final. Gervinho scored twice for the capital side.

Carles Puyol sits on the Barca bench, with his shaggy hair and luminous bib he looks like a guide dog. He claps his hands to rally the troops. At the moment, it's pretty subdued in Catalonia.

I'm going to throw this one out there - is the Nou Camp the most visually impressive football stadium in the world? A vast arena, a playing area the size of a meadow, with a carpet of emerald green graced by twinkle-toed artists. Most impressive grounds in the world? Answers on a postcard? Though a tweet or text will do.

Matt in Hull: I've never seen such a one-sided 0-2. PNE much the better side! Looks like Forest have used the rest of their luck for this season in that 2nd half!

Will in Nottingham: I disagree with Dan - Preston outplayed the home team at City Ground. And lower league sides have a right to be cautious in away games in the FA Cup.

Back under way in the Nou Camp, Barcelona leading 10-man Real Sociedad. Could be a long half for the men in blue.

Tom in Preston: Re: Dan in Nottingham (21:52) 'never seen such a negative performance' what do you call that second half display from Forest?

I think we have started a 'who deserved what' debate over that Preston-Forest tie...

Alistair Wiseman:, external Disgraceful from ref again. Barca should be down to 10 and a pen against them. Instead, they score and somehow Martínez sees red!

I'm seeing replays of the penalty incident that so enraged Real Sociedad. Javier Mascherano was trying to swap shirts with Carlos Vela while the Mexican ran through on goal. Probably should have been a penalty and a red card.

Ross in Norfolk: Preston unlucky? Kevin Davies should of been sent off in the first half and Cox had a goal incorrectly ruled out for offside at 1-0.

Dan in Nottingham: To be fair, if you'd seen the first tie, there is no way Preston deserved a replay. I've rarely seen such negative unadventurous football.

James, exasperated PNE fan: Sorry, but how was it not a cricket score to North End? Credit to Forest though, made the most of the opportunities they had!

I'm getting a fair bit of grief for suggesting that Preston deserved an equaliser. I'm just calling it how I see it, but I certainly take the point that if you don't take your chances, you can't be classed as unlucky.

Nottingham Forest striker Jamie Paterson speaking to BT Sport: "You are never always going to play well and the manager let us know that at half-time. We were a little lucky not to concede but we dug in and showed another side of our character."

Image source, Getty Images

So only one of our Wednesday cup trilogy remains active, and in that we have reached the halfway stage. Barcelona lead 1-0, but Real Sociedad are feeling more than a little injustice.

Former Stoke defender Danny Higginbotham on BBC Radio 5 live sports extra

"Nottingham Forest won that game through their defence. They stood strong with Preston throwing the kitchen sink at them. It was a very professional performance from Forest. We saw two sides of them - the attacking prowess, but also the defensive grit and determination.

"That is a hallmark of Billy Davies' sides. He demands nothing else."

What a horrible couple of minutes for Real Sociedad. Before they can kick-off, Inigo Martinez is sent off for protesting against Barca's goal. It probably has something to do with what happened at the other right before the goal, when Carlos Vela looked to be pulled back when through on Jose Pinto. Nothing got given. Barca then went and took the lead.

Finally, Barca have an opener, much to the relief of the Nou Camp. From a corner, the ball is nodded to Sergio Busquets, who turns in unchallenged.

Tom in Preston: Story of Preston's season. All the possession, no end product!

And, with that, we'll have Sheffield United boss Nigel Clough taking on the former club of both himself and dad Brian. Cup romance.