Real Madrid were held to a 1-1 draw away from home by relegation-threatened Cadiz.
Following an amazing run by Rodrygo, Mariano put the 35-time Spanish winners up after five minutes.
Before halftime, Cadiz’s Ruben Sobrino equalized deservedly.
Real goalie Andriy Lunin stopped Alvaro Negredo’s second-half penalty, leaving Cadiz outside the relegation zone on goal difference heading into their last match.
Real Madrid manager Carlo Ancelotti made six changes and rested key players, including Luka Modric and Karim Benzema, ahead of their Champions League final against Liverpool in Paris on Saturday, 28 May. However that did not stop them thrashing Levante 6-0 in midweek.
Real Madrid may be free of domestic pressure after winning the league title with four games to spare at the end of April.
On Sunday, though, they faced a considerably tougher test as a determined Cadiz team fought for their La Liga status.
Lunin, who replaced Thibaut Courtois for the visitors, made six stops as the hosts attempted 21 shots on goal.
Cadiz were unable to add to Sobrino’s score as Negredo missed a penalty after being taken down by Lunin – the Real goalkeeper diving to his left to save the Spaniard’s spot-kick.
Mallorca’s 92nd-minute winner over Rayo Vallecano brought them level on 36 points with Cadiz, who know they must match Mallorca’s result next Sunday because to their 12-goal advantage in goal difference.
Real Madrid have maintained a 12-point lead over Barcelona following a goalless draw at Getafe.