Once again weighed down by its defensive wanderings, FC Barcelona lost in overtime on Wednesday to Athletic Bilbao (4-2) with two goals from the Williams brothers qualifying the Basque team into the semi-final of the Copa del Rey.
The elder Inaki, returned expressly from the CAN after the early elimination of Ghana, crucified Barça (106th, 3-2), before his younger brother Nico definitively sank the Catalan club with an outside right in full skylight to seal the success of the Lions (120th 1).
A goal which plunges the Catalan club a little further into crisis, left behind in La Liga (3rd, five points from Real Madrid and eight from Girona) and humiliated in the Super Cup final against its Madrid rival (4-1).
Trailing from the 36th second of play in San Mamés, Xavi's men completely missed their start, as on too many occasions this season, demonstrating the current great excitement of the reigning Spanish champions.
Guruzeta's goal after a scramble in the area is already the third conceded by the Blaugranas in the first minute of play this season in all competitions.
Still overtaken defensively by the conquering Basques and carried by their supporters, Barça nevertheless managed to get back into the match with a gag goal from Lewandowski by countering the clearance from Yuri Berchiche (26th, 1-1).
The Barcelonans even took the advantage on a gem from the young Lamine Yamal, who curled perfectly from the left after having transplanted into the axis from his right wing (32nd, 2-1).
The 16-year-old prodigy was once again the only one capable of bringing some spark to Barça's soporific possession game, who never seemed to want to push to drive the point home.
Trailing at half-time against the run of play, the Basques put pressure on returning from the locker room and equalized through Sancet, alone within five meters to head a caviar from Nico Williams (49th, 2-2 ).
The whirling Yamal almost saved his team by scoring a double, but missed two face-to-face encounters with the Basque goalkeeper (65th, 86th).
And extra time favored the locals, who did not stop attacking while their opponent seemed to be heading towards a penalty shootout.
Inaki Williams first crucified Barça in two stages (106th, 3-2), before a fourth goal scored by his younger brother Nico (120th 1).
Earlier in the evening, Mallorca qualified for its first Cup semi-final in more than 20 years by inflicting its second defeat of the season on Girona (3-2) under the eyes of Rafael Nadal.