A last-minute winner from captain Xabi Prieto saw Real Sociedad win a seven-goal thriller against Sevilla 4-3 to pick up their first win in four matches.
Imanol Agirretxe volleyed David Moyes' side in front shortly after a quarter of an hour but Timothee Kolodziejczak headed in an equaliser just before half-time.
Prieto restored La Real's lead from the penalty spot at the start of the second half but Sevilla turned the game around thanks to a header from Carlos Bacca and a penalty from substitute Kevin Gameiro.
However, with nine minutes remaining, Alejandro Arribas put the ball through his own net to make it 3-3 and Prieto struck again in injury time to decide the game.
The defeat is a huge blow to Sevilla's hopes of qualifying for the Champions League next season as they slip five points behind Valencia in fourth spot, while La Real move on to 27 points, eight clear of the relegation zone.
Sevilla made a strong start to the game but it was Real Sociedad who took the lead after 16 minutes when Joseba Zaldua got down the right and crossed towards the middle of the box and Agirretxe side-footed home on the volley.
Unlike when they got an early goal against Barcelona in January, Moyes' side did not sit back and had several chances to score a second, the best which fell to Sergio Canales. The former Real Madrid man was released by Agirretxe with just Sergio Rico to beat but he shot straight at the goalkeeper.
The hosts would regret missing those opportunities as Kolodziejczak headed in an inswinging corner from Gerard Deulofeu, beating Ruuli at his near post.
Real Sociedad were able to restore their lead just a few minutes into the second half when Tremoulinas wrestled Canales to the floor when defending a corner. Prieto stepped up to take the penalty and calmly chipped the ball down the middle as Rico committed himself.
Sevilla then twice came close to getting another equaliser. First, Ever Banega sent in a free-kick which sailed to the back post and all Alejandro Arribas had to do was tap in, but the centre-back got too far under it and sent it over the bar. Then Daniel Carrico let fly from over 30 yards and his shot came crashing against the far post.
But another goal for the visitors did not look far away, and arrived in the 68th minute. Again Banega launched a free-kick into the area and Bacca powered it into the top corner with his head, injuring himself in the process.
Sevilla then came to within inches of a winner. Ruuli came out to thwart Diogo Figueiras down the right side of the area and appeared to foul the defender but the ball dropped to Tremoulinas and Ansotegi headed the Frenchman's shot off the line to keep his side in the game.
Sevilla took the lead for the first time in the game when Inigo Martinez blocked a shot with his elbow and Gameiro squeezed his penalty under Ruuli's right arm to score.
However, the game was far from over. Prieto put in a dangerous cross from the right which caused havoc in the box and the ball was eventually turned in by Arribas. Denis Suarez then missed a chance to win it for Sevilla and at the other end Pablo Hervias went for goal from 20 yards and was denied by a finger-tip save by Rico.
It was from that resulting corner that the game was won. Ruben Pardo aimed a corner to the near corner of the six yard box and Prieto headed past Rico to decide an enthralling match.