Barcelona were left stunned as Nelson Haedo Valdez struck twice to give promoted side Hercules a famous 2-0 win at the Nou Camp.
Valdez gave the Alicante-based outfit the lead when he poked home from a free-kick against the run of play after 26 minutes. And the Paraguay forward, making his debut for the visitors, silenced the Nou Camp with a superb second on the hour to give Hercules a two-goal lead.
Barca attacked ceaselessly in the final half hour, but came up against an inspired figure in the Hercules goal. Keeper Juan Calatayud produced a string of fines saves to deny Lionel Messi, Pedro and David Villa as the visitors held on.
They could have extended their lead at the death but French striker David Trezeguet missed an open goal.
Jose Mourinho enjoyed a winning home debut as Real Madrid got their Primera Division campaign up and running with a narrow 1-0 victory over Osasuna.
Centre-back Ricardo Carvalho netted the only goal of the game just after half-time to give Madrid the spoils in a match they dominated but struggled to finish off a battling Osasuna side. A lacklustre first half showing ended with the team being jeered from the pitch.
The result lifts Madrid onto four points after Mourinho, who has not lost a home match in eight years during his time at Porto, Chelsea and Inter Milan, saw his side held goalless at Real Mallorca in their season-opener a fortnight ago.
When asked about the reaction of the fans at half-time, Mourinho said: "They pay me, the fans can whistle when they want to. I will continue doing my job and one day try to give total satisfaction to the fans. I will never have a negative word about the fans of Real Madrid.
"I prefer the support of the fans in difficult moments, but I will never criticise. I understand that the fans want more, I also want more and the players want more.
"We've controlled the game easily, without any problems. That only thing we've lacked is some calm and clarity, which will come with time and work. I'm sure we would have been calmer if we had gone 2-0 up. I'm going away happy with the three points and with the total control of the game. I was on the bench without any type of pressure or fear.''
Valencia continued their 100% start to the Primera Division season with a hard-fought 1-0 home win over Racing Santander.
Hedwiges Maduro's header on the stroke of half-time proved enough for Los Che, who downed Malaga 3-1 in their first La Liga match a fortnight ago. Racing, in contrast, remained without a point following their 3-0 opening defeat at home to champions Barcelona.
Atletico Madrid survived a nervy finish to claim a deserved second successive league victory at Athletic Bilbao to top the fledgling table.
The prolific Diego Forlan set them on their way and Tiago looked to have killed the game off in the 80th minute. But Fernando Llorente's goal put the encounter back in the balance and the hosts could have pinched a point in the closing stages.