Barcelona manager Hansi Flick shouldered the blame for his team's 4-2 LaLiga defeat at Osasuna on Saturday, acknowledging that his decision to rest key starters contributed to their first loss of the domestic season.

Leaders Barcelona entered Saturday's game on the back of seven consecutive wins to start the LaLiga season but were stunned by an Osasuna side that were lethal on the counter attack with Ante Budimir scoring a brace and Bryan Zaragoza a constant menace.

"You have to accept these defeats. We didn't play very well. I think it's my responsibility," Flick told Movistar Plus.

"(With the rotations) I tried to protect the players, because they have been playing a lot of minutes. But I didn't expect us to play like this."

Flick acknowledged that Barcelona made numerous mistakes and credited Osasuna for their performance. He expressed frustration over the second goal, which he believed was preceded by a foul, but emphasized the need to move forward.

"To score four goals against us is too much, but I've told the team that we have to keep going. It's a busy schedule and we are on the right track."

Flick was referring to a challenge by Osasuna midfielder Lucas Torro, who stood on Pau Victor's foot, in the buildup to Zaragoza scoring their second goal in the 28th minute. The goal was given as neither the referee nor the VAR saw an infringement.

Barcelona midfielder Pedri echoed Flick's sentiment, expressing frustration over the perceived foul and acknowledging the need to improve.

"For me it is a clear foul," a visibly frustrated Pedri told Movistar Plus.

"It's normal to make (team) rotations, there are a lot of matches. It's no excuse. We had to go out with 11 players and the score at halftime penalised us."

Pedri acknowledged Barcelona's poor first-half performance and their inability to respond effectively to Osasuna's counter-attacks.

"The first half we were not good. We didn't come out to the game well. In the second half we deserved a bit more, but goals came when we were at our best."

"We had to go for the game... after halftime. We had to go for everything and on the counter-attack they hurt us.