Chelsea were champions last season and the sharp decline has led to the inevitable speculation that Mourinho will be sacked by an owner with a reputation for firing managers.

Chelsea owner Roman Abramovich was at Stamford Bridge for the capitulation, with Mourinho believing the result might have been different had Radamel Falcao been awarded a penalty, rather than booked for diving.

“I think it’s time for people to be honest and say that I’m right,” Mourinho told Chelsea TV. “Maybe I’m going to be punished but I have to say it, because my players and the supporters deserve me to say it... we don’t get one decision from the referees. One.

“We lost in Porto with a big penalty in the last minute in the face of two officials. We had a big penalty that the referee should be here, speaking to you, explaining why he did not give the penalty. A crucial penalty.

“They don’t give. Never. They are afraid to give. We were punished by that.”

The FA will likely wait till Monday, at the earliest, to decide whether to act on Mourinho’s comments.

Southampton were excellent as Steven Davis cancelled out Willian’s opener before Sadio Mane and Graziano Pelle struck.

Mourinho believes his team is “very fragile” and crumbles like a “castle of cards”.

He said: “The team emotionally is very fragile. The team is feeling too much the pressure of the bad results, the negativity, the fact every time you make a mistake you are normally punished.

“When we make individual mistakes the team is like a castle of cards that collapses, because mentally the team is in trouble. The confidence levels are very low and the team is feeling that a lot.”

Mourinho was apologetic that he cannot play for Chelsea himself and admitted he is uncertain about the reasons behind Chelsea’s downward slide.

He added: “I’m so sorry that I don’t have a game tomorrow. I’m so sorry that I am too old to play and I have no quality to play in a team like Chelsea.

“I am so, so sorry because I would love to play. I don’t know what is good or bad for them in this moment.”

Davis’ goal was his first for club or country since February 2014.

The Northern Ireland midfielder said on saintsfc.co.uk: “I thought I’d save the goal for a good occasion. It has been a frustrating time, but I had a good chance early on and snatched at it.

“I was disappointed with that. It was a great lay-off from Graziano and it was nice to see it hit the back of the net. ”Hopefully it’s the start of a few more to come.“

Davis praised a fine team display in victory.

“It was a great performance and a deserved three points,” he added.