An exquisite Luis Suarez volley sealed a hard-fought 1-0 win for champions Barcelona at Athletic Bilbao in their La Liga opener as Luis Enrique's men gained a measure of revenge for their 5-1 aggregate loss in the Supercopa de Espana.
Despite Athletic's stubborn defending in the third encounter between the sides this month, Barca took the lead early in the second half through Suarez's venomous strike.
A combative but lacklustre first half was punctuated by Lionel Messi's penalty miss just after the half-hour mark, the spot-kick having been awarded in dubious fashion after Suarez took a tumble in the area.
Defending champions Barca grew into the game in the second half, controlling much of proceedings after taking the lead, though their bad luck with injuries continued as Sergio Busquets had to be carried off on a stretcher and Dani Alves was also substituted with a knock.
Athletic struggled to pose a threat as the game wore on, with Messi almost adding a second in the closing stages, but it was nonetheless a winning start for Barca.
Rafael Benitez endured a difficult Real Madrid debut as his new-look side were held 0-0 by La Liga newcomers Sporting Gijon at El Molinon.
The former Napoli boss has the task of building on Carlo Ancelotti's successful tenure at the Santiago Bernabeu, but the Spaniard has work to do on this showing as his revamped forward line failed to break down an organised Sporting side.
In the absence of the injured Karim Benzema, Jese started up front in a 4-2-3-1 system – ahead of Gareth Bale, Isco and Cristiano Ronaldo.
And while Real dominated first-half possession, it was Sporting who went closest to the opener when Antonio Sanabria saw a header rattle the crossbar 10 minutes before the break.
The Paraguay forward seemed to think the ball crossed the line after rebounding down, while Carlos Carmona headed a glorious chance wide early in the second half.
But Real were left to settle for a point as they lost early ground to Barca and city rivals Atletico.
Also on Sunday, former Liverpool attacker Iago Aspas scored a 77th-minute winner as Celta de Vigo won 2-1 at a 10-man Levante.
Debutant Roberto Soldado was on the scoresheet as Villarreal were held to a 1-1 draw at Real Betis.