Willy Caballero admits Manchester City team-mate Martin Demichelis felt responsible following the 1-0 derby defeat to Manchester United on Sunday.
Demichelis endured a dismal game at the Etihad Stadium, having been left for dead by Marcus Rashford for the teenager's first-half goal before being fortunate not to concede a penalty for bundling the striker to ground inside the area.
A loose backpass from the Argentine almost gifted Anthony Martial a goal just after half-time and goalkeeper Joe Hart was forced off on a stretcher after damaging his calf when clearing the danger.
"I know Martin well and he is a really professional player," Caballero said afterwards. "Unfortunately, he feels really bad now about himself, and about the game, but he now has to go to Argentina for the international games, so I wish him all the best.
"We are a team, and when I have made a mistake and we have lost, I feel the same. The most important thing is not who makes mistakes, but who tries to react for the team.
"In this case it could have been Martin, but everyone makes mistakes during the season. We are a team and have to react, and to take our chances."
City's defeat means they are just one point above West Ham and United in the race for the Premier League top four.