Chelsea manager Maurizio Sarri and captain Cesar Azpilicueta apologized after beating Manchester City 6-0.
City led 4-0 after 25 minutes as Chelsea lost their third game in a row.
The Blues slipped to sixth in the Premier League table, under Arsenal's goals.
"In the last three games we played very badly, so we have to apologize," said the 69-year-old Italian.
Sergio Aguero completed his hat-trick with a 56th-minute penalty, before Raheem condemned Sterling to his worst defeat at a late second moment since losing to Nottingham Forest 7-0 in April 1991.
"It's one of the worst nights in my career," added defender Azpilicueta (29). "It's hard to explain what happened.
"We have a lot of goals and we can not accept that, I can only apologize to the fans because it's unacceptable."
Sarri, who left Napoli's Serie A squad last summer to take the lead at Stamford Bridge, was asked if he was worried about his own future.
"I do not know," he said. "You ask me [about] something that is not my job. I'm worried about our achievements, not the club. You would have to ask the club.
"I want to study, I want to understand, I do my best and the players do their best, for the moment I just have to apologize."
We are in trouble – Sarri
Chelsea was unbeaten in 18 games after beating City in the Community Shield 2-0. They have since lost seven out of 21 in all competitions.
"I'm surprised because we played better at home earlier this season than at home, I do not know what happened, but we're in trouble at the moment," added Sarri.
"In the last three or four games we had no reaction from the first difficulty, so we have to understand.
"It's difficult to describe our performance, it's also difficult to understand, we started well, but after four minutes we confessed a goal in a stupid way.
"We just had to stay in the game, but the reaction was not good, and in the 20 minutes after the first goal, we made a lot of mistakes against the wrong opponents because they played fantastic football."