That was truly remarkable. The best team in the world getting an absolute pasting. Plenty for Luis Enrique to mull over ahead of the new La Liga season. But before that, he's got the second leg to worry about. Join us for live text commentary of that on Monday evening. Until then, adios!
- Aduriz nets a hat-trick
- San Jose opens scoring with superb strike from halfway
- Opening match of Spanish football season
- First leg of Spanish Super Cup at San Mames; second leg at Nou Camp on Monday
- Get involved : tweet #bbcfootball or text 81111
Goodness me, I'm not sure I can remember a match quite like that. Gentle curtain-raiser? The curtains have been ripped clean off the walls by that Athletic performance. They'll have high hopes of improving on last season's seventh place after a display like that.
Well, that is the quite the marker laid down ahead of the Spanish football season. A huge statement by Athletic Bilbao. As for Barcelona, they have massive work to do after conceding four goals for the second game in a row.
Mikel San Jose, who started this madness, goes into the book. And that's it! Barcelona have been humiliated! What an extraordinary performance from Athletic Bilbao.
Into added time now. What a job by Ernesto Valverde's men. The San Mames is jumping in the pouring rain.
Gurpegui, who has a nose like a boxer who's been in one too many fights, picks up a yellow for a shirt tug on Iniesta. The kind of peccadillo he's built a career on.
Pedro looks forlorn on the bench. If he didn't want that Manchester United move before, I bet he does now.
More defensive reinforcement for Athletic Bilbao. Eneko Boveda trots on for Markel Susaeta. If Athletic can just stop Barca scoring an away goal in the next five minutes, they've surely got this won.
Tell you what, this can't be doing much for Barcelona's confidence ahead of the new La Liga season. They get their league campaign under way next Sunday. Their opponents? Athletic Bilbao. Right here at the San Mames. Tasty.
Javier Mascherano goes in the book for a ragged tackle on Susaeta. Mascherano holds one finger up, as if to indicate that it's his first foul. Sure it is, Javier, sure it is.
That one was against Barcelona as well. Bilbao lost 5-1 on aggregate...
Bilbao new boy Javier Eraso is off, replaced by veteran Carlos Gurpegui, who is 35 next week. He'll add defensive ballast in the closing stages.
Lionel Messi has had a quiet night tonight, and when he does get a rare glimpse of goal, Aymeric Laporte is there with a superb block.
It's Friday night in Bilbao. It's a national fiesta tomorrow. They're beating Barcelona 4-0. Quiet night then?
Sandro is on for Pedro for Barca. Bilbao's Markel Susaeta goes into the book for a late tackle.
Unbelievably, this is the second game in a row in which Barcelona have conceded four goals, after their 5-4 Uefa Super Cup win over Sevilla. They'll do well to win this one, even over two legs...
Late foot in by Jabier Etxeita, and that earns him a yellow card...
I think it's fair to say that we won't be seeing the central-defensive partnership of Thomas Vermaelen and Marc Bartra again. They've been woeful...
Aritz Aduriz steps up and nervelessly slots the ball into the bottom corner. He's taking home the match ball this evening. What an extraordinary scoreline.
Dani Alves drags his man down at the near post as a corner comes in, and that's a penalty!
Lekue is on for Sabin, who has had a magnificent game.
What do Athletic do now? Go for the kill? Or shut up shop and hold on to what they've got? The signs are that they can tear Barcelona apart here - Eraso wins a corner with a menacing run straight at the heart of the defence.
What a night in Bilbao! Barcelona aren't just on the ropes, they're on the canvas! Barcelona fail to deal with a cross into the box, the ball drops to Aritz Aduriz, and the striker swivels and dispatches a superb strike into the corner of the net. Dare I say it, but tie over?
No surprise, Luis Enrique withdraws another youngster: the largely anonymous Sergi Roberto is hooked, and Ivan Rakitic is on in his place. Can he make a difference?
Rain teeming down in Bilbao now. This is turning into a very uncomfortable assignment for Barcelona.
Just prior to that goal, Andres Iniesta replaced Rafinha for Barca. Luis Enrique is wheeling out the big guns.
What a crucial sixty seconds in this tie! Barely a minute after Iraizoz denied Messi with that superb save, Athletic go straight up the other end and score. It's great work by Sabin down the left, he leaves the defence trailing, stands up a superb cross and Artiz Aduriz absolutely monsters Javier Mascherano in the air and plants a superb header into the net. This may be a two-legger, but we very much have an upset on our hands.
And again Barca go close! Luis Suarez scampers down the right and pulls the ball perfectly in to the path of Lionel Messi, whose shot is brilliantly tipped away from the bottom corner by Iraizoz.
And just seconds after he could have been traipsing off the pitch for an early bath, Pedro comes within an inch of levelling this tie. A bouncing ball causes confusion in the Bilbao defence, Pedro latches on to it, takes a good first touch and sends a rasping shot against the crossbar.
Goodness me, Pedro is walking a tightrope. He's already been booked, and he jumps for a header with Xabier Etxeita and sticks his arm right into the defender's face. He looks pleadingly at the referee, who keeps his cards in his pockets. Lucky, lucky boy.
No changes at the break, by the way. How long will Luis Enrique keep his powder dry?
We're under way in the second half.
Right then. Nearly ready for the second half. Should we expect a Barca backlash?