Laurent Koscielny has laid bare the crisis of confidence at Arsenal and admitted the players’ self-belief will not return swiftly after Brighton inflicted the team’s fourth defeat in the space of 11 days.

“We know we are in a bad situation, a bad period,” Arsenal’s captain said. “We tried but nothing is with us. We tried to fight and play football but you could see the confidence is very down. We miss a lot of things during the game but we need to push more again and again. The confidence will be back slowly. We know we need to win to have a little bit more confidence in us. We lost a little bit of our quality but we need to stay united.”

Arsène Wenger has accepted that a top-four finish is out of the equation, which means Arsenal need to win the Europa League to return to the Champions League. They play the first leg of their last-16 tie against Milan in Italy on Thursday.

“It is very hard because when you play for a big club like Arsenal you need to be in the top four,” said Koscielny, who was moved to tears at a team meeting called last week to address the slump. The defender said the defeat at Brighton capped the worst week of his career, coming as it did after Manchester City beat Arsenal in the Carabao Cup final and Premier League.

“I think it has been difficult for everyone, maybe the first time for all of them,” Koscielny said. He did not hide from the impact. “We are not confident in our quality individually and collectively,” he said.

Wenger has been the target for much of the fans’ anger, which surfaced again in chants for the manager’s sacking on Sunday, but Koscielny said blame was shared. “The players have the responsibility on the pitch, the boss has responsibilities too and we have to be together,” he said. “It is difficult to say if it is his fault or our fault. The club are together and we need to stay together.”