On Saturday, Barcelona lost points after a disappointing 1-1 draw against Alaves away from home.
Barcelona, having a thumping start to their campaign with a 4-0 victory over Villarreal, now has just two wins in six games.
Fans have started showing their frustration towards manager Ronald Koeman, who was appointed after Barcelona's heartbreaking 8-2 defeat against Bayern Munich in the Champions League.
While Koeman is a vital part of the new Barcelona project, the fans have taken to Twitter and started the trend #KoemanOut.
Here are some reactions:
Koeman, meanwhile, said he is worried about the team's performance in attack.
"I'm worried by our performance in attack. It's not an attitude problem, nor concentration, but it's a question of being more assured in front of goal," Goal.com quoted Koeman as saying.
"It happened to us against Juventus and today as well. Furthermore, we gifted Alaves their goal. But if we create that many chances, we can't miss so many. If you create chances and you only score one, it's not good," he added.
Alaves took the lead in the match after Luis Rioja scored a goal in the 31st minute of the match. However, Barcelona managed to level the score with the help of Antoine Griezmann's second-half strike.
Koeman further stated: "I think the play has been, in general, very satisfactory. I'd be more worried if we weren't creating chances. We have to perform better in front of the goal. The final pass, the final shot. We can't miss so many [chances]. We're missing too many."