A new-look Atletico Madrid suffered a setback in their opening La Liga match of the season when they squandered several chances and twice struck the post in a 0-0 home draw with Osasuna on Sunday.
As the strike-hit season finally got under way a week late, Athletic Bilbao's bow at their San Mames arena was spoiled by promoted Rayo Vallecano, one of four Madrid-based clubs in the top flight, who fought back from a goal down to earn a 1-1 draw.
Michael Laudrup's Real Mallorca made a winning start with a 1-0 victory over visiting Espanyol, while the club the former Denmark international used to coach, Getafe, drew 1-1 at home to Levante.
Last weekend's first round of matches fell victim to industrial action called by the players' union (AFE) over unpaid wages, a dispute with the league (LFP) that was finally resolved on Thursday.
Champions Barca begin their bid for a club record-equalling fourth title in a row at home to Villarreal on Monday (1900 GMT), when former Arsenal captain Cesc Fabregas could make his league debut.
In brilliant sunshine at a festive Calderon, Atletico midfielder Eduardo Salvio was guilty of poor finishing and curled an effort off the upright in the first half, while former Arsenal winger Jose Antonio Reyes hit the post with a powerful swerving shot shortly after the break.
Osasuna goalkeeper Andres Fernandez pulled off a string of fine saves to deny the home side and Atletico were fortunate substitute Nino opted for power rather than precision in blasting wide from close range at the death.
Madrid's second club have seen Argentina striker Sergio Aguero and Spain Under-21 goalkeeper David De Gea depart for the English Premier League, while Uruguay forward Diego Forlan looks poised to join Serie A side Inter Milan and was not included in the squad.
Atletico also have a new coach in Gregorio Manzano, who has brought in players including club record-signing Falcao of Colombia, Turkey midfielder Arda Turan, who came off the bench to make a second-half debut, and Spanish Under-21 striker Adrian.
"We dominated a large part of the match," Manzano said.
"We created goal-scoring chances and we should have taken them to change the final result."
In the three matches played on Saturday, Valencia snatched a thrilling 4-3 comeback win at home to Racing Santander, Real Sociedad held on with 10 men to beat Sporting Gijon 2-1 and Real Betis beat fellow promoted side Granada 1-0.