Defending champions Atletico Madrid got their Spanish Liga season underway with a 2-1 win at Celta Vigo on Sunday as Barcelona braced for "a leap into the unknown" without Lionel Messi.
Atletico win opener as Barcelona 'leap into unknown' without Messi
Life after Lionel: Barcelona's players warm up before the Spanish League match against Real Sociedad
Angel Correa gave Atletico the lead after 23 minutes after being set up by Thomas Lemar.
Correa added a second goal in the 64th minute just five minutes after Iago Aspas had pulled Celta level from the penalty spot.
However, the game was marred by a mass brawl in the closing stages following a foul on Atletico striker Luis Suarez.
Red cards were brandished for Hugo Mallo of Celta and Mario Hermoso of Atletico.
Barcelona fans were, meanwhile, contemplating their post-Lionel Messi future which was starting with a home encounter against Real Sociedad later Sunday.
Messi may have joined Paris Saint-Germain but his memory lingers heavy over the Camp Nou despite the removal of a giant photograph of the Argentine superstar from the entrance in the wake of his move to France.
A crowd of 25,000 was expected as part of ongoing Covid-19 restrictions and anger clearly remains in the wake of Messi's unexpected departure after 21 years at the Catalan club.
Some banners were in place well before kick-off venting the fans anger towards president Joan Laporta.
One read "Laporta, Barca is not your business", while another proclaimed "Barca yes, Laporta no!"
"It was a big emotional blow," said 23-year-old Barca fan Adria De Lucas.
"I was in my room when I saw the news. I started sending messages to all my friends, and no one believed it. It was emotionally hard."
He added: "It's a leap into the unknown (without Messi). We will see what happens."
As Barca try to fill the Messi-sized gap as well as ballooning debts of more than 1.2 billion euros ($1.6 billion) Real Madrid got off to a flier on the pitch as a brace from French veteran striker Karim Benzema helped bring a 4-1 victory at Alaves on Saturday.
The win, achieved with further goals from Nacho and Vinicius allowed Carlo Ancelotti, who gave Gareth Bale a start on his return from Tottenham, to celebrate the start of his second spell in charge with a victory.
A Joselu penalty for the hosts was a minor blemish after Real keeper Thibaut Courtois, making his 100th Liga appearance between the posts for Real, brought down John Guidetti.
Like Barca, their eternal rivals, Real last week voted against a plan for an investment fund to inject 2.7 billion euros of cash into La Liga for fear the accord will cramp their own ability to make money.
Bilbao and one other unnamed club also voted against but other clubs in the top two divisions were all in favour to allow the motion to pass.
In other action Saturday, Cadiz and Levante parted 1-1 as did Mallorca and Real Betis while the match between Osasuna and Espanyol ended in a goalless stalemate.
There are two matches on Monday as Villarreal go up against Granada while Elche meet Athletic Bilbao.
Valencia got the ball rolling Friday and pocketed three points after an early Carlos Soler penalty was enough to see them overcome Getafe 1-0.
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