La Liga champions Barcelona fell to their first opening day defeat of the season in 11 years when they were beaten 1-0 at Athletic Bilbao thanks to a sensational late overhead kick from veteran striker Aritz Aduriz.
The 38-year-old came off the bench late in the game and soon made Barca pay for squandering several chances by acrobatically lashing an unstoppable shot into the net in the 89th minute.
The Catalans were without injured captain Lionel Messi but lined up with 200 million euros of new talent in France forward Antoine Griezmann and Dutch midfielder Frenkie de Jong.
However, they lacked sparkle against an energetic Bilbao side that had the better run of play for the first half even though Barca came closest to scoring before the interval.
Luis Suarez struck the near post in the first half when presented with a terrible back pass from Athletic's Unai Lopez and was soon forced off with a calf injury, while substitute Rafinha rattled the crossbar after coming on.
Barca improved after the break as coach Ernesto Valverde replaced young midfielder Carles Alena with the more experienced Ivan Rakitic and spent most of the second period in the home side's area.
Rakitic and Rafinha each came close to scoring for the visitors but they were outdone by one of Spanish football's best loved players in Aduriz, who has announced that he will retire at the end of the season.
"Sometimes football is so beautiful and when you least expect it a ball like that comes to your feet and goes into the net," Aduriz told reporters.
"Barcelona are the best team around and it's very difficult to last a whole game taking them on and matching them for space but we knew exactly how to manage our energy."
It was the first time Barca have lost their opening game of the season since 2008, when they were beaten 1-0 by Numancia in Pep Guardiola's debut game in charge, although they swiftly recovered from that setback and went on to win the treble.
"This is a very difficult ground to come to and we were made to see how tough the competition is," said Barca defender Gerard Pique.
"We did not play like we usually do and they put us under a lot of pressure and if you're not at your very best then a team like Athletic walks all over you."
Lewandowski double rescues draw for Bayern
Bayern Munich’s Robert Lewandowski scored twice to save the champions’ blushes as they had to come from behind to rescue a 2-2 draw against Hertha Berlin in the Bundesliga season opener on Friday.
The Bavarians, who enjoyed a fine start and had early chances with Thomas Mueller and Thiago Alcantara, have only themselves to blame for failing to kill off the game early.
Last season’s league top scorer Lewandowski opened his account in the 24th minute, sliding in to complete a move he started himself, and become the first player to score on five consecutive season opening games.
But the visitors stunned the home crowd with two goals in three minutes.
First a deflected shot from Dodi Lukebakio, who had scored a hat-trick in Munich while playing for Fortuna Duesseldorf last season, wrongfooted keeper Manuel Neuer in the 36th minute.
Marko Grujic then completed a stunning turnaround in the 39th when he won an aerial challenge against Benjamin Pavard and charged through to beat Neuer.
Lewandowski’s penalty on the hour rescued a point for the hosts who pressed for a winner but failed to break through the populous Hertha defence again.
“We did not play badly. We had a lot of chances and then comes that first Hertha goal which was lucky,” Lewandowski told reporters.
“We were still a bit shocked from the first goal. We lost some pace and maybe our last pass was not as accurate but we played a good game overall.”
Lewandowski can now count on some reinforcements with Brazil midfielder Philippe Coutinho set to move to the German champions on loan from Barcelona, according to both clubs.
Borussia Dortmund, their main title rivals this season, play Augsburg on Saturday.