The Blues manager insists his side are not in a relegation battle but Mourinho's assessment of his players after a 2-1 loss at the King Power Stadium was brutally frank.
The champions' dismal defence of their title became even more desperate as they suffered a ninth league loss of the season.
The defeat leaves Chelsea an eye-watering 20 points behind the table-topping Foxes and only one point above the bottom three.
After showing signs of recovery in recent weeks with four clean sheets in the five matches leading up to the visit to Leicester, Chelsea returned to the jaded-looking languid form they had frequently displayed previously.
Leicester deserved their victory, and Mourinho admitted as much but remained defiant about the bigger picture
"At the moment we are in a zone where I feel ashamed," said the Portuguese.
"A relegation battle? No I don't believe this
We are in the relegation zone - an area in the table
But to be in a battle is to be there for three or four months and I don't think this will be so."
Chelsea's fall from grace is remarkable - they stand 16th in the table - and Mourinho offered an explanation that asked fresh questions of his players.
"One possibility is that I did an amazing job last season and brought the players to a level that is not their level and now they can't maintain it," he said.
"One of my best qualities is that I can read the game and identify the strengths of the opponent and tell my players what they are
So it is a big frustration to accept the goals because my work was betrayed, if that is the right word.
"I worked four days on this match
I prepared everything related to the opponent
I identified four movements where they scored almost all their goals.
"My players got all that information, you can ask them, they are honest guys who will tell you it is true
But in the situations I identify, we concede the first and second goal
The mistakes were there.
"But Leicester fought with everything and defended with everything and they deserved it."
Superb goals from Jamie Vardy and Riyad Mahrez gave Leicester victory
Substitute Loic Remy pulled one back for Chelsea with 13 minutes left but the champions were unable to find an equaliser.
The win saw Leicester move two points clear at the top of the table but Foxes boss Claudio Ranieri is not getting carried away, insisting his team still need five more points in order to guarantee their Premier League status for another season.
"We are top of the league but I want five more points," said former Chelsea manager Ranieri
"You laugh, but I do
And I don't know where these five points are going to come from
Everton, Liverpool, Manchester City, Bournemouth and Tottenham are all very tough games
"Let me achieve 40 points and then I will look at the next goal
The fans are dreaming but they have to dream, not us."
Leicester midfielder Danny Drinkwater hobbled off after just 17 minutes on Monday night but Ranieri hopes he will be fit for the trip to Everton at the weekend.
"It is a little problem with his hamstring but I hope he can be ready for the next match," said the Italian
Source : PA
Source: PA