Sergio Ramos' late penalty helped Real Madrid win against 10-man Real Betis 3-2 after the video assistant referee spotted a handball in the La Liga.
The handball was called against Betis defender Marc Bartra when VAR revealed he touched the ball with his arm during a brush with Madrid substitute Borja Mayoral in the area.
It seems Mayoral's attempt to kick the ball pushed Bartra's arm into the ball.
Ramos converted the spot kick for the 82nd-minute winner.
Madrid played with an extra man from the 67th when Betis defender Emerson was red-carded for fouling Luka Jovic with only the goalkeeper to beat.
The referee's decision was also aided by video.
Karim Benzema, the heart of Madrid's title run last season, once again led the side.
He set up Federico Valverde for the 14th-minute opener and scored his own goal early in the second half after Betis went ahead 2-1.
Aissa Mandi and William Carvalho scored for a Betis that had won its first two matches under new coach Manuel Pellegrini. Midfielder Sergio Canales provided key passes in both Betis goals.
Valencia stumbled to a 1-1 draw at home against plucky promoted side Huesca while Alaves earned their first point of the season in a dull 0-0 draw with Getafe at Mendizorroza.
Barcelona, Atletico Madrid and Sevilla all open their league campaigns on Sunday after having their first two rounds postponed for playing in European competition in August.
Australian Associated Press