A 94th minute goal by Betis striker Antonio Sanabria gave his side a 1-0 win away to Real Madrid in the Santiago Bernabeu stadium and produced one of the shocks of the season in Spain.
Cristiano Ronaldo returned for Real Madrid, who were looking for a home win after two consecutive draws in the Liga Santander in front of their fans.
However, a combination of poor finishing, bad luck and good saves from Betis keeper Antonio Adan kept them at bay as they laid siege to the Betis goal in the second half and Zinedine Zidane’s side were caught by a sucker punch by the Paraguayan, who moments earlier had seen a goal correctly ruled out for being offside.
The defeat leaves Madrid seven points behind Barcelona at the top of the Liga Santander.
Elsewhere, Jesus Navas’ late goal took Sevilla up to second in the table with a 1-0 win over a Las Palmas side that had won their last two games.
Clinical finishing from Angel Correa and Yannick Carrasco in the second half gave Atletico Madrid a 2-1 win away to Athletic Club Bilbao, who saw a first half penalty from Aritz Aduriz saved by Jan Oblak and who pulled a late consolation goal back from Raul Garcia.
Deportivo la Coruna claimed their first win of the season as a Luisinho strike on the stroke of halftime gave them a 1-0 win at home to Alaves, who remain without a point or a goal after the first five games of the campaign.
Meanwhile, Leganes and Girona fought out a dull nil draw in which the visitors had the best of the few chances created.
Tuesday saw Leo Messi score four goals as Barcelona thrashed Eibar 6-1 in the Camp Nou Stadium with the other two goals coming courtesy of Denis Suarez and Paulinho, who like Suarez has now scored two goals in his last two games.
Simone Zaza also scored a hat-trick as Valencia hammered Malaga 5-0 in the Mestalla Stadium, a result which leaves Malaga coach Michel Gonzalez in danger of losing his job after 5 defeats in as many games.