Real Sociedad fired blanks in a 0-0 draw with Cadiz on Friday, unable to consolidate third place in La Liga, leaving the door open for Atletico Madrid to overtake them.
The Basques had the better of the game but their stubborn opponents, 14th and three points above the relegation zone, held out for a valuable point.
Real Sociedad, who have held third place since November, could fall behind Diego Simeone's Atletico, fourth, if the Rojiblancos beat Sevilla on Saturday.
The hosts dominated possession at the Reale Arena and Carlos Fernandez came close with an effort which flew narrowly off target before the break.
Majestic veteran playmaker David Silva returned from injury as a substitute, as did striker Mohamed-Ali Cho, although neither could help La Real break down the visitors.
Cadiz almost broke the deadlock when Roger Marti rounded goalkeeper Alex Remiro but struck the post with his effort from a tight angle.
The Andalucians suffered a setback when defender Fali was taken off on a stretcher late on, having sustained a worrying injury when Mikel Merino accidentally crashed into him from behind at a corner.
It led to 11 minutes of stoppage time and Alexander Sorloth had a fine chance at the end to snatch the three points for La Real but lashed over from close range.
