La Liga is back this weekend, but not quite as you know it.Six games are being played across the opening matchday — but the Spanish top flight’s two biggest clubs, Barcelona and Real Madrid, will not be in action.Allow us to explain…Who is playing in the opening La Liga weekend and who is not?The opening game is Deportivo Alaves v Getafe today (Saturday) at 7.30pm local time (6.30pm UK, 1.30pm ET), with Sevilla hosting Rayo Vallecano later that evening.Racing Santander will make their La Liga return on Sunday when Villarreal travel to their El Sardinero home ground, while Espanyol play Levante that day. Another historic club back in the division, Deportivo La Coruna, welcome Elche on Monday, before Atletico Madrid face second-division play-off winners Malaga on Wednesday.Racing Santander made an emotional return to La Liga (Juan Manuel Serrano Arce/Getty Images)Four matches from the opening gameweek have been pushed back to late August due to an agreement between La Liga and Spain’s players’ union, the AFE, which includes a mandatory break for all players whose international teams reached the World Cup semi-finals.Spain reaching and winning the final against Argentina on July 19 means players such as Barcelona’s Lamine Yamal and Real Madrid’s Marc Cucurella will not have games until at least the second weekend of the season.When do Barcelona and Real Madrid actually start their seasons?La Liga champions Barcelona begin the defence of their crown at Elche on Sunday, August 23, allowing the eight Barca players in Spain’s World Cup-winning squad more time to recover.Jose Mourinho’s first game of his second spell as Madrid manager will be at Espanyol on Saturday, August 22.What were supposed to be the Clasico duo’s first matches are now being played towards the end of the month — with Barca hosting Bilbao’s Athletic Club at the Camp Nou on Thursday, August 27, and Madrid taking on Real Sociedad at the Bernabeu on Wednesday, August 26.Barcelona contributed eight players to Spain’s World Cup-winning squad (Eric Verhoeven/Soccrates/Getty Images)Many top players involved in the World Cup have only returned to training in recent days — Yamal, Pedri, Dani Olmo and Pau Cubarsi had their first training session back at Barca on Wednesday.