Manchester City have won the English Premier League title without even playing on Sunday after nearest challenger Manchester United were shocked 1-0 loss at home to bottom-placed West Bromwich Albion.
The defeat took City to 16 points clear of United.
"I trust in my work, that is for sure".
He said: "We won the Carabao Cup and that was a step in the right direction for me but to be competing in the Premier League since I was 19 and to play all the games I played in the Premier League, to not win the Premier League, it was a bit devastating for me not to have won it with Tottenham". The last Premier League was not 20 years ago, it was three.
"Whatever you read, I know what really happened". You win, of course, with quality, but with consistency in every level, not just the performance level but also the mental level. "Today was a very bad day and we need to move on".
The irony that this is exactly how Manchester City play will not be lost on anyone.
"I know that sooner or later that would be and if I was in that position I would be very upset if somebody say they won the title because Manchester United lost to West Bromwich Albion", said Mourinho.
City midfielder Kevin De Bruyne, a candidate for Player of the Year, said: "Unbelievable season for us".
'We didn't want or played simple, everything was slow, one more flick, trick, turn.
"The first time you think you are going to win all of them and the first time you lose it you think you are never going to win it again. When we had the ball, we wanted to run, dribble and everything was complicated", he said.
In his second season in charge, Guardiola, aided by the vast financial backing of City's Abu Dhabi-based owners, has created a sublime team that helped him become the first Spanish coach to win the English top-flight title.
Mourinho was hardly effusive in his praise when asked about City's success, but did concede they deserved to be champions.
It is ironic that United came back from 2-0 down against City themselves last weekend to win 3-2 and delay City's party, only to surrender so tamely on home soil.
The debate will now rage as to whether this City team is the greatest the Premier League has ever produced, and it is one that has no undisputed answer, with the best teams of United, Arsenal and Chelsea all having their justifiable claim to that title. They saved the best for last, with substitutes Teddy Sheringham and Ole Gunnar Solskjaer scoring in stoppage time to stun Bayern Munich in the Champions League final in Barcelona.