And the wall does its job. Corner to Barca, taken by Neymar to the near post but Sociedad clear. 

Headed debate on the Barca bench, which includes the likes of Andres Iniesta. Lionel Messi is brought down and has a free-kick 25 yards out, pretty central. Looks dangerous.

There's a minute's applause before kick-off at the San Siro as a tribute to Cesare Maldini, the iconic former Milan and Italy defender and manager, who died last weekend at the age of 84.

Incoming Chelsea manager Antonio Conte, the current Italy boss, is among the spectators tonight, as we get under way.

Barca looking a bit narrow so far, and when Dani Alves comes out to the right side he is caught offside from Javier Mascherano's diagonal. Looked close on replays. 

Some great tackling from the hosts. They are not giving Barca time to think, let alone settle, on the ball. 

Another attack from Sociedad with Carlos Vela making the running this time. He crosses but Javier Mascherano does well to head clear. Sociedad not content to sit back. 

Great play from goalscorer Mikel Oyarzabal, who leads a Sociedad counter-attack single-handedly and wins a throw-in in the corner. The type of play you see in the final minutes, not the first 15, but maybe an insight into what type of game we have in store now. 

Lionel Messi gets a kick on the ankle from Alberto de la Bella. Sociedad furious in defence so far. 

Barca enjoying a spell of possession now. I say enjoying, Luis Enrique looks a bit twitchy in his green parker, straight from Manchester's Northern Quarter.

Image source, EPA

Mario Balotelli, very much on the fringes at the San Siro these days, is given a chance in attack as AC Milan attempt to erase the memory of last weekend's 2-1 defeat at lowly Atalanta. 

Juventus are without the suspended Sami Khedira; Kwadwo Asamoah is chosen ahead of Stefano Sturaro in midfield.

Milan XI: Donnarumma; Abate, Alex, Romagnoli, Antonelli; Honda, Montolivo, Kucka, Bonaventura; Bacca, Balotelli.

Juventus XI: Buffon; Barzagli, Bonucci, Rugani; Lichtsteiner, Pogba, Marchisio, Asamoah, Alex Sandro; Mandzukic, Morata.

Chance for Barca now in a blistering start to this game. Lionel Messi lashes over from about 12 yards out. It was on his right foot, but still, he had time to hit the target. 

Robust start from the hosts, who are pressing from the front. But Barca beat it and Munir has an early chance but Geronimo Rulli saves in the Sociedad goal. 

Barca in a rhubarb and custard kit, get us under way. 

Image source, EPA

Back to La Liga and you may have heard that Cristiano Ronaldo became the first player to reach 30 league goals in six successive seasons earlier today.

Meanwhile, Lionel Messi can reach goals for club and country if he scores today. Funny how these boys are always going head-to-head for record headlines. 

As well as Barcelona's trip to San Sebastian, we will also keep you across Juventus' trip to AC Milan where the Serie A leaders can extend their six-point gap to second placed Napoli, who are in action on Sunday. 

Juve have won 20 out of their last 21 league games.  

Image source, #bbcfootball

I said earlier that Barca lead the table by four points from Real Madrid. That has now been cut to three points after Atletico Madrid's 3-1 win at Espanyol to move Diego Simeone's side into second.  

As previously mentioned, Luis Suarez is suspended and with the second leg of Barca's Champions League quarter-final against Atletico Madrid to come on Wednesday, Luis Enrique has made five changes to the team which beat Diego Simeone's lot last Tuesday. 

Barcelona XI: Bravo, Alves, Pique, Mascherano, Rafinha, Busquets, Turan, Munir, Sergi Roberto, Messi, Neymar. 

Real Sociedad, led by former Barca B coach Eusebio, no less, include former Arsenal forward Carlos Vela in the team.

Sociedad XI: Rulli, Gonzalez, Reyes, De la Bella, Elustondo, Illarramendi, Granero, Prieto, Vela, Zurutuza, Oyarzabal.

There are reports that Barcelona's players consider this game as crucial. Win at the Anoeta and they will be seven points clear with six games left. 

Three of those games are at the Nou Camp  - against Valencia, Sporting Gijon and Espanyol, while the away games are at Real Betis, Deportivo La Coruna, Granada.  

Looks relatively straight forward on the face of it, but then who knows what might happen this evening?

Image source, Epa

For now, we'll overlook the fact that leaders Barca have double the number of points (76) that ninth-placed Real Sociedad have earned this season. 

Luis Enrique has pointed to his side's last five La Liga trips to Sociedad which reads: played five, lost four, drawn one. 

As you can tell from Barcelona training this week, it's got the players worried!