Change for Sociedad as Joseba Zaldua comes on for Aritz Elustondo. Approaching 10 minutes left. Barca taking their foot off the pedal for a bit now. 

Balotelli has the bit between his teeth now, though. Juraj Kucka wins the ball from Claudio Marchisio and sets up the Milan striker on the edge of the area to whizz a shot just over. Good spell of pressure from the home side.

More drama. Milan's Carlos Bacca turns and shoots on the edge of the area - and Gianluigi Buffon gets down brilliantly to save. Mario Balotelli is following in, and must score. But no! Buffon recovers to turn on to the underside of the bar. Balotelli is on to teh loose ball to turn into the net - but it is clear he has punched it in. The striker is booked for handball.

Lionel Messi goes very close to scoring his 500th goal for club and country. He has time and space to shoot about 10 yards out, but Geronimo Rulli dives to his left to stop it. To be fair, he didn't have to dive too far either. 

Messi, seemingly, not at the races tonight. 

Collision between Carlos Vela and Jordi Alba in the Barca penalty area, but from the hosts' point of view the free-kick goes the wrong well. 

Sergi Roberto is replaced by Ivan Rakitic. 

Jordi Alba is traditionally a left-back but he's a left-winger right now as his team-mates aim to find him on the diagonal. Neymar then goes into the book for a scything tackle.

If the second half is as good as the first, we're in for a treat.

Barca slowly stepping it up now with Sociedad remaining in their own half. Andres Iniesta has the ball in the net after Neymar nods it back to him on the edge of the box, but the Brazilian fouled a Sociedad defender in doing so, so the goal does not count. 

This is very close. Barca win a free-kick 25 yards out just to the left of the D, perfect for a right-footer. So up steps Neymar, who gets the free-kick up and over the wall, but it's wide by about six inches. 

Jordi Alba makes a dart in behind on the left as the ball is cut out. But it already shows what his introduction will add to the Barca team. 

Sociedad's pressing has definitely dropped in its intensity, which is kind of expected after that first period. Jordi Alba is now on in place of Arda Turan. 

Another thing Andres Iniesta's introduction has helped with, is stopping Lionel Messi dropping too deep to look for the ball. 

Iniesta then has time and space to shoot from 25 yards, his shot is well saved; it was heading for the top corner. 

A really enjoyable first half. AC Milan have shown the application and spirit that was missing in defeat at Atalanta last week, but Juve got stronger as the half wore on. Tough one to call this; but Juve might just be favourites to win this.

Andres Iniesta has put a different slant on this game already. Sociedad do not seem to be pressing him with the same intensity as he helps force a corner before passing to Munir, whose shot is well saved despite being called for offside. 

Juve could have gone in front right at the end of the first half. Paul Pogba, who has been pretty well shackled by Juraj Kucka so far, breaks free for once and finds Stephan Lichtsteiner bursting forward from the right-back spot. Lichtsteiner approaches the goal at an angle, but has a fair amount of target to aim at, so it is disappointing to see his shot whizz well wide of the far post.

Lionel Messi, who has looked a little out of sorts tonight, then mis-times a connection following Andres Iniesta's chipped pass. The Barca forward thought he was offside, but he wasn't, and holds his head in his hands. 

Andres Iniesta involved in Barca's attacking play straight away as he feeds Neymar on the edge of the box. The ball is worked to Sergi Roberto, whose cross is headed clear ahead of the arriving Arda Turan, who commits a foul and was booked in the first half. 

The possession stats are in Juventus' favour as the first half comes to a close. They have had 56% of the ball to Milan's 44%. The leaders have just about had the edge since going behind, but it is anyone's game, this.

Sociedad on the attack from the off. David Zurutuza, so impressive in the first half, clips the ball forward to Carlos Vela, who is near the goal-line but cannot find a team-mate from his cut-back. 

The hosts get the second half under way.