Barcelona made a losing start to the defence of their La Liga title, slipping to a 1-0 defeat to Athletic Bilbao without Lionel Messi at San Mames on Friday.
A spectacular 89th-minute winner from Aritz Aduriz compounded Barca's misery on a night when Messi missed out because of a calf problem, while Luis Suarez was withdrawn with a similar injury, and summer signings Antoine Griezmann and Frenkie de Jong struggled on their league debuts.
Athletic did most of the running early on, buoyed by the support of a raucous home crowd, as well as the energy and brilliance of Inaki Williams. The forward went close after just seven minutes, but Marc-Andre ter Stegen turned his fine effort away from goal.
Williams was causing havoc with his direct running and close control. Not for the first time, though, quality end product eluded the gifted forward:
Andy West @andywest01
Watch out for Iñaki Williams. Has the potential to become one of the best strikers in the world, no exaggeration. Pace, power, technique, versatility, intelligence, workrate. Only defect is finishing. If that improves he'll be world class and I get a feeling he's ready to explode
The visitors were off the pace but should have punished Williams' profligacy when a defensive gaffe let in Suarez on 31 minutes. Inexplicably, the normally prolific No. 9 managed to curl his shot on to the outside of the post.
Suarez struggled to carry the fight without Messi's influence and inspiration. He needed the support of Griezmann, but the former Atleti star was taking his time to get up to speed.
Griezmann's case wasn't helped by a lack of service from midfield. De Jong was expected to pull the strings in a deep-lying playmaker role, but Athletic had a rude greeting in store for the ex-Ajax ace:
An already-stunted Barca attack ran into further trouble when Suarez had to be removed. The club later confirmed the extent of the 32-year-old's injury:
Suarez's replacement, Rafinha, almost made the breakthrough when he saw a shot crash off the bar as the half drew to a close.
Knowing he needed more from his midfield, Ernesto Valverde brought Ivan Rakitic off the bench. The playmaker wasted two excellent chances to score, first heading an Ousmane Dembele corner over before smashing a shot into the clouds amid a scramble in the box with 20 minutes remaining.
Barca couldn't find the scoring touch, but Valverde's injury-hit side was hanging tough against committed opposition.
Valverde's critics were nearly silenced in the 80th minute when Rafinha glided past multiple defenders, but he saw Athletic goalkeeper Unai Nunez rebuff his low effort. It was Nunez to the rescue again moments later when Griezmann was teed up by the raiding Jordi Alba.
Missing so many chances came back to haunt Barca when evergreen Aduriz pounced in the penultimate minute. The 38-year-old connected with a scissor-kick to beat Ter Stegen.
Aduriz's contribution continued his superb, goal-littered career with Athletic. It also raises questions about the strength in depth of Barca's squad.
While there's no denying Messi and Suarez rate as huge losses, players with the reputations and price tags of Griezmann, Dembele and De Jong should be good enough to still earn a creditable result against teams such as Athletic Club.
Barca host Real Betis at the Camp Nou on August 25, while Athletic are away to Getafe a day earlier.