Antonio Rudiger says Chelsea were stupid in what was a “disaster” of a result against Leicester.
The Blues started the season with a 12-game unbeaten Premier League run, but have now lost three of their last six matches.
Their most recent defeat came at the hands of Leicester, with Jamie Vardy scoring the game’s only goal.
Rudiger believes the result was a “disaster”, with the club now level on points with fifth-placed Arsenal and 11 points behind Liverpool.
“For us in this situation, in the table, it is a disaster,” he told BBC Sport.
“With respect [to Leicester] if we cannot win these type of games, we cannot compete.
“It is simple, these teams know how to fight, they are killers. One chance, one goal today. Against Wolves, two chances, two goals. Simple.
“It’s a lack of mentality, I don’t know. Not clinical enough and just stupid.”