This could easily have silenced the home crowd.

No-one closes down Mikel Oyarzabal, who runs and runs, then thrashes a shot just over the angle.

Have Real Sociedad weathered the storm or are there more pelters to come?

They manage a rare break forward and Nacho Monreal sees a left-footed drive from the edge of the box deflect wide.

It wrong-footed goalkeeper Marc-Andre ter Stegen.

Another change for Sociedad.

Igor Zubeldia on for Diego Llorente.

20 minutes left.

Just not having for Barca in the final third.

A lovely shuffle from Lionel Messi, playing the ball off into the path of Jordi Alba.

The marauding full-back zips is across the six yard but Ivan Rakitic cannot convert, sliding in at the far post.

Think Gazza v Germany at Euro 96.

Chances coming now for Barcelona.

Gerard Pique stays up for a corner and is found in the six yards box by Lionel Messi's cross, but the ex-Manchester United defender heads straight at goalkeeper Alex Remiro.

Closest we have come to a goal.

Antoine Griezmann inadvertently plays the ball into the path of Ivan Rakitic outside the box and the Croatian rockets a first-time shot towards the near post but Alex Remiro dives to his left to push the ball away.

Excellent stop.

From ex-Arsenal man Nacho Monreal.

Sackable offence.

Both Barca centre-backs booked now as Gerard Pique's name is taken for a barge into the back of Mikel Merino.

A scramble in the box after Antoine Griezmann heads down, and Lionel Messi hooks over from eight yards out.

Under plenty of pressure.

A change for the away side.

Ander Barrenetxea makes way for Mikel Oyarzabal.

Wow, never seen this before.

Sociedad flood the box with blue and white shirts - in an almost 4-4-2 formation.

It means Lionel Messi have little to aim at and the second line of defenders can nod the ball away.

Brilliant tactics.

Big trouble here for Sociedad.

Mikel Merino barges over Lionel Messi on the edge of the box.

Booking for the skipper but Barca have a free-kick in a very dangerous position.

Decent chance for Sociedad as Alexander Isak ghosts in behind and pulls the ball back for Martin Odegaard, but the Norwegian wants too much time on the ball and screws wide.

Oof, very close.

Brilliance from Lionel Messi, trapping the ball with his left foot then shifting it onto his right on the edge of the area, but curling a yard wide.

A glimmer of a chance for the visitors at the start of the second half, Ander Barrenetxea cutting in from the left but blazing over.

Can Sociedad keep Barca at bay?

Can they grab a goal themselves?

Let's find out.

Away we go for the second half.

Image source, Rex Features

Some half-time reading for you...

Alexander Isak's performances for Real Sociedad suggest he is set to be a major star for years to come.

He is tall, prolific, and blessed with magnificent technical ability. In a way, his skillset is comparable to Zlatan Ibrahimovic's.

But in terms of their personalities and playing style, the comparison is totally wrong.

Actually, they couldn't be more different.

Read the full piece

Goalless.

Barca assistant Eder Sarabia is on the touchline, giving instructions to his side.

He is wearing ripped jeans.

Thoughts?

Thumbs up for cool dude, thumbs down for 'put some trousers on lad'.

Petulance from Lionel Messi, diving in very late and high on Sociedad skipper Mikel Merino to earn a booking.