Barcelona suffered their first defeat of the La Liga season against Athletic Bilbao on a famous night at the new San Mames.
Iker Muniain grabbed the game's only goal when he converted Markel Susaeta's cross after 70 minutes.
It was Barcelona's second defeat in a week, following their loss Wednesday at Ajax, while Athletic continued their unbeaten record at their new home.
Just three points separate Spain's top three now, with Athletic a little way back in fourth.
Here are the major talking points from a fascinating match in the Basque Country.
It's mad that after the defeat to Ajax in the Champions League, Gerardo Martino's effect on Barcelona is being scrutinised.
As Guillem Balague wrote for B/R in the week though, that is the case:
"What you’re getting is a Barcelona playing too direct, unable to press high up the pitch, with too many long balls and without the players to hold the ball up and win the 50-50 challenges."
This was again evident in the defeat against Athletic Bilbao as La Blaugrana sought diagonals to open up the Basque side.
And while it is, of course, hyperbole to seriously worry about a manager who has lost just twice in 22 games since arriving in Europe, it is evident there are question marks, despite what the league table says, over this Barca team.
It's going to be a long week for the Argentinian—this columnist recommends he stays away from Catalan papers Sport and Mundo Deportivo.
While Barcelona's performance will be the major talking point, it should be noted that Athletic Bilbao were very impressive.
Markel Susaeta, in particular, was brilliant at San Mames in Athletic's famous win over the Catalans.
The 25-year-old was a constant threat down the right flank, regularly giving Adriano problems and dragging Barcelona's centre-backs out of position.
So, it was no surprise that he played a major part in the winning goal.
Finding space on the right side of the 18-yard box, Susaeta's wicked delivery was turned beyond Jose Pinto by Iker Muniain.
There's no doubt about who the man of the match was.
Barcelona managed just two shots on target Sunday night against Athletic Bilbao.
For a team featuring the likes of Neymar, Alexis Sanchez and Cesc Fabregas, that is too few—is it too much to expect one of them to stand up?
Neymar was the liveliest.
The Brazilian drew a good save from Gorka Iraizoz in the first half and was taken down by Ander Iturraspe on the edge of the area in the second period when well placed.
He was also culpable of wasting the ball though, while his choice of footwear meant he had problems staying on his feet in the opening 35 minutes.
Sanchez wasn't poor, but he didn't manage a shot on goal, while Fabregas didn't find the spaces a false nine might be expected to find.
It's not a case of with or without Lionel Messi, merely a case of a bad night at the office for Barca's front three—not to mention some good defending from the home side.
Barcelona's defending didn't cost them three points in Basque Country, but should Marc Bartra feel disappointed to have found himself parked on the bench for the second match running?
The young central defender had been afforded an extended run in the side of late, and his form was good enough to warrant a call up to Vicente del Bosque's Spain squad.
He's since been left out of Barca's matches against Ajax and Athletic Bilbao.
And while Javier Mascherano is largely solid in the back four, he's not without moments of weakness in most matches.
Inside the first 10 minutes at San Mames, he was skinned and left out of position by both Iker Muniain and Markel Susaeta.
It seems Barca won't buy a defender, but they won't put their faith in Bartra either.
While it is true Athletic Bilbao were missing the suspended Aritz Aduriz Sunday night against Barcelona, the point still stands that the Basque side miss a forward.
Iker Muniain and Markel Susaeta looked dangerous out wide and Ander Herrera showed glimpses of creativity in the middle, but Gaizka Toquero didn't carry a threat up front.
Neither has Aduriz until recently.
The 32-year-old, who was prolific last year, has scored just three goals this season, although they've all come in the last five matches.
Ernesto Valverde will wonder how many his side would have won by with a goalscorer on the end of some of the chances they created against Barcelona—say Fernando Llorente.
Maybe Sunday night was different.
Different because it was Athletic Bilbao, one of La Liga's most historic clubs; different because it was Barcelona's first visit to the new San Mames; different because Athletic's fans really know how to stir up an atmosphere.
But it doesn't have to be different. Teams don't have to lay down against Barcelona.
One of the main arguments against Spain's top flight is that the big guys have it far too easy, and it's often hard to argue with that.
However when Athletic, admittedly one of the league's better sides, take the game to Barca like a cup final, you have to wonder why more don't do the same.
Too often, particularly at Camp Nou, teams seem accepting of their defeat before kickoff.
“We have left the dentist, bring in the next one,” said Levante manager Joaquin Caparros earlier this season, via Football Espana.
Barcelona, Real Madrid and even Atletico Madrid don't need to be viewed like that though—Villarreal, Espanyol, Osasuna and now Athletic have all proved they're not invincible.