Real Sociedad defeats Barcelona after Lewandowski's goal is controversially disallowed, while Yamal misses the game.

La Liga leaders Barcelona lost 1-0 to Real Sociedad on Sunday after a disputed goal from Robert Lewandowski was disallowed; coach Hansi Flick called the call a "big mistake." Earlier, Atletico Madrid defeated Mallorca 1-0 thanks to Julian Alvarez, moving the Rojiblancos up to third place.

After playing an additional game, Barcelona's second league loss of the season was sealed by Sheraldo Becker's goal in the 33rd minute, leaving the Catalan powerhouses six points ahead of Real Madrid in second place.

Lewandowski's initial goal was denied.

After Lewandowski's first goal was disallowed, there was intense discussion about whether or not the Polish forward was offside.

"We have to accept that it was the wrong decision," Flick said on the club's streaming service, Barca One.

"It wasn't the referee's fault; we all make mistakes as humans, and today was a major one."

Teenage sensation Lamine Yamal was sidelined for Barcelona's Champions League victory over Red Star Belgrade due to an injury to his ankle, which severely hindered his play.

For the first time this season across all competitions, the Catalans were unable to score in a game as eighth-place Real Sociedad held firm and Barcelona failed to muster a single attempt on goal.

"We are accountable for this loss; we are capable of playing much better," Flick said.

Barcelona midfielder Pedri told Movistar, "It's a tough place to go, where La Real push a lot… we have to learn from our mistakes and that's all."

We usually score goals, but today we weren't accurate. I believe this will be an isolated incident, and we'll be more accurate in the games that follow.

"I don't care that the team isn't scoring; I think they're playing well."

While defender Pau Cubarsi played in a mask following a cut that required stitches on his face in Serbia, playmaker Dani Olmo began on the bench.

The Catalans were given another uncomfortable night in the Basque nation after struggling in San Sebastian in the past.

After 13 minutes, Lewandowski thought he had put Barcelona ahead when he scored after a good reaction to a blocked shot, but a VAR review disallowed the goal.

Lewandowski did not seem to be in front of Real Sociedad defender Nayef Aguerd, but referee Guillermo Cuadra Fernandez was informed that the attacker was offside.

The front of Lewandowski's boot was off according to La Liga's semi-automated offside technology, but Spanish media vehemently disputed whether the technology had mistakenly read Aguerd's heel as a component of the seasoned striker's footwear.

Dominant La Real 

After Barcelona's goal was chalked out, the home team had the upper hand and repeatedly put visiting goalie Inaki Pena to the test.

Pena's fingers were stung by Takefusa Kubo's low drive following a delicate dribble inside from the Japan international's right flank.

Luka Sucic nodded the ball into Becker's path, and he finished coolly and low to put Real Sociedad ahead.

At halftime, Flick replaced the ineffectual Frenkie de Jong with Dani Olmo, but Barcelona was still in second place.

Ander Barrenetxea surged into the area and squeezed an effort wide from a tight angle, while Becker blasted a shot wide after Jules Kounde did just enough to throw off the Real Sociedad winger.

Barcelona failed to reach the net or even generate any real threat in the closing minutes, even though they had scored 40 goals in their first 12 league games.

Brais Mendez, a midfielder for Real Sociedad, stated, "We really wanted to win at home and there was no better team to do it against."

"The supporters deserved a night like this, and they are the best team in Europe."

In a close match at Mallorca's Son Moix stadium, Diego Simeone's Atletico team won their fourth straight game in all competitions.

After being generously set up by Diego Simeone's son Giuliano Simeone, Alvarez scored his fourth league goal since moving from Manchester City to Atletico in the summer in the 61st minute.

Argentina international Alvarez stated, "We improved in the second half, the goal came, and we took three important points. We knew it would be a tough game."