Barcelona lost their second straight game without injured star Lionel Messi on Sunday when Athletic Bilbao handed the defending La Liga champions a 1-0 loss at San Mames.
Forward Iker Muniain scored the winner in the 70th minute after Bilbao's incessant pressure recovered the ball and sparked a counterattack inside Barcelona's half.
Neymar was once again tagged to pick up Messi's goal-scoring duties, but when he wasn't frustrated by slippery footing, Bilbao's defense got the better of him.
Barcelona were left level on points with Atletico Madrid and three points ahead of Real Madrid after both title rivals won Saturday.
Barcelona lost their first game of the season Tuesday at Ajax in the Champions League. They hadn't suffered consecutive defeats since March.
Carlos Bacca scored one goal and set up Kevin Gameiro's late winner to lead Sevilla to a 2-1 win at Granada.
Bacca put Sevilla in front at Los Carmenes Stadium in the 23rd minute when he took a ball lost by Granada's Jeison Murillo and used the outside edge of his right boot to curl an exquisite strike around goalkeeper Roberto Fernandez.
Granada surged forward and Antonio Beto was called into action several times before Granada's Yacine Brahimi finally beat the Sevilla goalkeeper from the penalty spot in the 61st minute after Daniel Carrico had handled in the area.
With the action flowing up and down the pitch, Gameiro went on in the 81st minute and Bacca headed on Beto's goalkick for the French forward to drive past Fernandez three minutes from time.
Valencia forward Jonas scored a hat trick after Osasuna were reduced to 10 men to ease the hosts to a 3-0 win.
Jonas netted all three of his goals on the first touch to increase his team-leading tally in league play to eight goals this season.
Valencia were helped when Osasuna's Patxi Punal saw a direct red card in the 16th minute for a studs-first tackle into Dani Parejo's lower leg.
Rayo Vallecano's Alberto Bueno scored his second goal in injury time to secure a 2-2 draw at Real Betis.
Defender Antonio Amaya headed Betis ahead in the 27th and Ruben Castro thumped the ball off the crossbar in the 51st minute.
Bueno went on in the 23rd and leveled in the 52nd by poking in a rebound which Betis goalkeeper Guillermo Sara let fall in the six-yard box.
Joan Verdu appeared to have restored Betis' lead for good in the 82nd. But Bueno controlled Jonathan Viera's lob with his right foot before firing home with his left one minute into stoppage time.
Betis' draw left them struggling in last place and winless in the past eight rounds while Rayo moved out of the relegation zone and into 17th.