Jorge de Frutos scored the first goal of the new La Liga season to set Rayo Vallecano on their way to a 3-1 win over 10-man Girona on Friday.
In the night's late game Real Oviedo's return to the topflight, after a 24-year absence, began on a flat note with a 2-0 defeat at Villarreal.
Rayo's Spanish winger de Frutos struck with his right foot from close range in the 18th minute, with Alvaro Garcia adding a second a couple of minutes later.
Girona's goalkeeper Paulo Gazzinga earned the unenviable distinction of picking up the first red card of the 2025/26 campaign when the Argentinian was sent off two minutes from half-time.
His foul on de Frutos led to Isi Palazon converting the ensuing penalty.
Girona pulled one back just before the hour when Joel Roca shot into the top left corner after an assist from Viktor Tsygankov.
Rayo finished eighth last season to earn qualification to the Conference League marking their return to European competition for the first time since 2001.
Later Real Oviedo's La Liga comeback began badly when Alberto Reina was sent off after picking up a second yellow in the 27th minute.
Two minutes later Cameroon forward Etta Eyong headed the home side into the lead, Pape Gueye adding a second before the interval.
Champions Barcelona begin the defence of their title on Saturday at Mallorca.
Real Madrid kick off life under their new manager Xabi Alonso against Osasuna on Tuesday.