Barcelona manager Ronald Koeman has insisted that his side should be too good to concede goals like the shocker they allowed in Saturday's 1-0 loss to Atletico Madrid.
In stoppage time of the first half, Marc-Andre ter Stegen came flying out of his goal and was left stranded as Yannick Carrasco easily beat the German to the ball and tapped it through his legs, and Carrasco slotted home into an open goal from all of 35 yards.
Barcelona did have a lot of the ball but failed to create many good chances, allowing Diego Simeone to record his first league win against Barcelona and just his fourth in 29 attempts in all competitions.
"We played well in the first half, but a team like Barcelona cannot concede a goal in the 47th minute like we did," Koeman said (via Marca). "The players are working well, but we want better results.
"In principle we have done our best. Then we had two very clear chances to equalise. It's always difficult, we know that Atletico defend very well. The goal [we conceded] was our fault; it's not good and it can't happen."
The defeat means Barcelona have fallen to tenth in La Liga, picking up just 11 points from a possible 24 this year.
The downward spiral which became clear towards the end of Quique Setien's time at Camp Nou has continued under Koeman. When pressed on what needs to change, the Dutch boss almost seemed spoilt for choice.
"Like any coach I am responsible," he admitted. "We know that we have to improve the results and we have to trust the players I have. We must improve in attack and defence. We know that we need to go on a run of winning matches."
Unfortunately for Koeman, the defeat isn't all he has to worry about. Centre-back Gerard Pique went off injured around the hour mark, while right-back Sergi Roberto appeared to pull up after striking the ball late in the game.
Barcelona took to their official website to reveal that Pique has sprained his knee, while Roberto injured his right thigh. Both players are set for further tests, but Koeman admitted he is fearing the worst.
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"I'm worried like any coach," he said. "There are a lot of injuries these days because of the schedule we have. "I will wait until tomorrow to see how the two players are doing; I don't know if they will be out for a while."