MADRID, Sept. 16 -- FC Barcelona are the only club in Spain to maintain their 100 percent record following the fourth round of matches in the Liga Santander over the weekend.
The return to league action after the international break presented Barca with a difficult trip to face Real Sociedad, who were playing the first game in their newly renovated Anoeta Stadium.
An emotional day was made even more so as the home fans paid homage to striker Imanol Agirretxe, who was forced to retire at the start of the season due to injury.
Real Sociedad were clearly motived or the game and with Barca resting Sergio Busquets and Phillipe Coutinho, the visitors were lacking fluidity and Aritz Elustondo put them ahead in the 12th minute with a powerful shot following a free kick.
Busquets and Coutinho were soon in the action in the second half, but Real Sociedad would have doubled their lead if Juanmi had been more clinical in front of goal before two bad errors from home keeper Geronimo Rulli gifted Barca the win.
Rulli missed two high balls in his area to leave first Luis Suarez and then Ousmane Dembele with simple chances to score and what could have been a memorable win for Real Sociedad turned into Barca's fourth win in four matches.
Real Madrid were unable to keep pace with Barca after being held to a 1-1 draw away to Athletic Club Bilbao, whose young goalkeeper Unai Simon produced an impressive display.
Iker Muniain put Athletic ahead after 30 minutes, but after he retired injured early in the second half, Madrid were able to take a better hold on the game and Isco equalized with a head erin the 63rd minute.
Atletico Madrid and Valencia are still struggling for form, with Atletico needing a 94th minute goal from debutant Borja Garces to save a point when it looked as if Sergi Enrich's 87th minute strike would give Eibar 3 points on their visit to the Wanda Metropolitano Stadium.
Valencia meanwhile remain winless after being held to a 0-0 draw at home to Betis.
Sunday lunchtime saw Villarreal claim their first win of the campaign with a 1-0 win away to Leganes thanks to Carlos Bacca's 65th minute goal, although the Guido Carrillo was guilty of sending a 49th minute penalty, which could have changed the outcome of the game, into the crowd for the home side.
Sergio Garcia's 52nd minute goal gave Espanyol a 1-0 win at home to Levante, while Ibai Gomez's 93rd minute strike gave Alaves a 1-0 triumph away to Valladolid who drop to the bottom of the table.
Getafe striker Angel Rodriguez scored two first half goal to allow his team to stun Sevilla 2-0 in Sevilla's Sanchez Pizjuan Stadium and the round of matches will finish on Monday when Girona entertain Celta Vigo, who could move second with a win in the Montilivi Stadium.