Jose Mourinho said he will not quit as Chelsea manager and told the club they must sack him if they do not want him in charge.
The Premier League champions lost 3-1 at home to Southampton, their fourth league defeat in eight games.
"I want to make it clear. One, I don't run away," said Mourinho.
"Two, if the club want to sack me they have to sack me because I am not running away from my responsibilities or my team."
Chelsea are 16th in the table, 10 points behind leaders Manchester City, who thrashed Newcastle 6-1.
"To be champions now is very difficult because the distance is considerable," Mourinho told Sky Sports.
"But I am more than convinced that we will finish in the top four, and when the season is so bad if you finish in the top four it is OK.
"Third - and I think this is even more important than the first and the second - it is a crucial moment in the history of this club.
"You know why? Because if they sack me they sack the best manager this club had."
'Referees are scared'
Chelsea took the lead through Willian but Steven Davis equalised before goals from Sadio Mane and Graziano Pelle secured Southampton's victory.
Saints appealed for penalties when Branislav Ivanovic appeared to pull Virgil van Dijk's shirt, while Ramires looked to have tripped Mane in the area.
The home side also had a penalty appeal rejected by referee Robert Madley when Radamel Falcao went over under a challenge by keeper Martin Stekelenburg.
"He was afraid to give it like everyone else is afraid to give it," said Mourinho.
"Why? Because there is always a question mark from you [the media] and always a critic so we are always punished.
"The penalty in this game is more than crucial because my team, at the moment, the first negative thing that happens... they collapse.
"After that the team lost even more confidence. Mentally, psychologically, the team is unbelievably down.
"If the Football Association wants to punish me they can. They don't punish other managers."
'Sadness brings sadness'
Chelsea's tally of eight points is their lowest after eight games in a top-flight campaign since 1978-79, when a win earned two points.
Only Sunderland have conceded more than Chelsea's 17 goals this season.
"They are players who are performing really, really bad individually. It is clear we are being punished by too many individual mistakes," said Mourinho.
"I assume my responsibilities. The players should assume their responsibilities.
"There are other people in the club that should also assume their responsibilities and to stick together. This is what I want.
"You know I have a big self-esteem and a big ego. I consider myself the best, having the worst period and worst results of my career.
"Doing that as a professional hurts me a lot and doing that at Chelsea hurts me twice. I want to carry on, no doubt.
"Sadness brings sadness and bad results attracts bad results."