The top two in Spain both lost this weekend as current La Liga champions Atletico Madrid closed the gap at the summit of the table to just one point.
Real Madrid took their 22-game winning run to Valencia on Saturday, but were beaten 2-1 at the Mestalla, which allowed Los Che to move fourth in the table.
Barcelona, meanwhile, lost at the Anoeta for the fourth time in five seasons as a Jordi Alba own goal gave Real Sociedad all three points.
Atletico were in on action on Saturday and Diego Simeone's side recorded a comfortable 3-1 win over Levante to move onto 38 points – level with Barcelona and just one point behind the leaders Real Madrid, who have a game in hand following their involvement in the Club World Cup.
Sevilla also continued their strong run on Saturday with a 1-0 win over Celta Vigo, but Villarreal's seven-game winning run ended as the Yellow Submarine threw away a two-goal lead at basement side Elche to share the points in a 2-2 draw.
Deportivo La Coruna eased their relegation worries with a 1-0 win over Athletic Bilbao, before Almeria concluded Saturday's action with a 2-1 victory over European hopefuls Malaga.
Rayo Vallecano won 2-1 at Getafe in the first match on Sunday, while Eibar's strong season continued as they beat Espanyol 2-1 in Barcelona.
On Monday, Cordoba moved into 18th position with a 2-0 win over Granada, who have dropped to second from bottom.
Here, Sports Mole picks out its 11 star performers from another weekend of pulsating Spanish action.
Diego Alves (Valencia)
The Brazilian goalkeeper proved unbeatable from open play in Valencia's 2-1 win over Real Madrid on Sunday. Los Blancos had a number of second-half chances, but could not find a way past Alves, whose star moment came in the latter stages when he expertly saved a point-blank Isco header.
Carlos Martinez (Real Sociedad)
The Spaniard was in the right place at the right time on more than one occasion during Sociedad's 1-0 win over Barcelona. Martinez made a number of crucial challenges at the Anoeta, while he helped nullify Barca's attacking threat in the second 45 minutes.
Inigo Martinez (Real Sociedad)
Martinez was the man-of-the-match in Sociedad's 1-0 win over Barcelona on Sunday. The centre-back simply did not put a foot wrong throughout the 90 minutes – frustrating Luis Suarez in the first period and Lionel Messi and Neymar in the second. Could do no wrong at the weekend.
Nicolas Otamendi (Valencia)
Scored the winner in Valencia's 2-1 win over Real Madrid, but it was the Argentine's work in defence that impressed the most. The centre-back was a tower of strength in the air and made a number of crucial interceptions. He has been one of the stars of La Liga thus far this season.
Guilherme Siqueira (Atletico Madrid)
The Brazilian seems to finally be filling the shoes of Filipe Luis, who left for Chelsea in the summer. The left-back delivered a sensational cross for Atletico's first of the match in their 3-1 win over Levante, while his energy down the left caused the visitors all sorts of problems.
Esteban Granero (Real Sociedad)
The Spaniard's career has been a bit up-and-down in recent seasons, but he seems to now be thriving at Sociedad. Granero was a key part of his side's 1-0 win over Barcelona, with the midfielder classy in possession of the ball and always willing to work across the pitch.
Andre Gomes (Valencia)
Could not find the back of the net despite a couple of golden chances during Valencia's 2-1 win over Real Madrid, but the midfielder's contribution was still of a very high level. Gomes dictated possession from a deep position and provided balance in Los Che's three-man midfield.
Florin Andone (Cordoba)
The 21-year-old had a league debut to remember on Monday as he scored Cordoba's second in their 2-0 win over Granada. The Romanian has only recently joined the first-team set-up at Cordoba, but his performance on Monday suggests that he is there to stay.
Antoine Griezmann (Atletico Madrid)
The Frenchman took a bit of time to settle at Atletico in the early part of the season, but he is now in fine form. A brace in his side's 3-1 win over Levante made it five goals in his last two league matches. Levante simply could not deal with the movement and guile of the attacker.
Jonathas (Elche)
The powerful forward gave the Villarreal defence nightmares during Elche's 2-2 draw with the Yellow Submarine on Saturday. Elche trailed 2-0 on their own patch, but Jonathas inspired the hosts to a comeback by netting the first and causing havoc in the final third.
Tomer Hemed (Almeria)
Hemed's double against Malaga on Saturday helped Almeria record three vital points at La Rosaleda. The hosts entered the match in fine form, but found the 27-year-old difficult to contain. Almeria will need the Israel forward in top form if they are to fight off relegation this season.
