Just five games into the season, the reigning champions have been beaten three times and his notoriously mean defence have already shipped 12 goals.
Everton’s Steven Naismith piled on more misery with a hat-trick in an impressive victory that moved the Toffees to the fringes of the Champions League places.
Whilst it is still unthinkable that Chelsea will be anywhere other than the top-four at the end of the season, Mourinho is already close to giving up hope of a reclaiming his crown.
“We need to improve a lot,” he said. “I don’t know if we can still win the title but I know we can win against Arsenal next week.”
The Portuguese says his side are short of confidence and insists a change in fortune will soon put his side back on track.
But barely 12 months after his side put down their marker for last season’s emphatic title triumph with a scintillating 6-3 victory at Goodison Park, Chelsea were sluggish and largely second-best.
Then Eden Hazard, Diego Costa and Cesc Fabregas had buzzed around Merseyside with a dynamic enthusiasm and creativity.
But on Saturday they were flat and short of ideas - comfortably shackled by a determined and gritty Everton defence expertly marshalled by the prodigious John Stones, whose price tag will have taken another significant hike.
“We need to win a couple of consecutive matches, we need to get our confidence back,” added Mourinho.
“We need the players to smile again and we need the central defenders to stop making mistakes. It is not easy to play football when your confidence is low.
“We are a team playing with doubts, because of the bad results we have had and because everything is going against us. I agree we are making mistakes, but at the moment it seems every mistake we make is getting punished.”
However, it was Roberto Martinez who had suffered an early setback when he was forced into an early change after Muhamed Besic picked up a hamstring injury.
But instead of introducing the Belgian winger Kevin Mirallas to square up to out-of-sorts full-back Branislav Ivanovic, the Everton boss opted for the rugged Naismith and it proved an inspired decision.
The Scot put the home side ahead in the 18th minute when he and Ross Barkley passed the ball simply around a static Chelsea midfield before drifting past the visitors’ defence to head in Brendan Galloway’s cross.
They almost doubled their lead within two minutes but Asmir Begovic - in for the injured Thibaut Courtois - made fine saves to keep out Aroune Kone’s close-range header and James McCarthy’s 20-yard strike.
But they didn’t have to wait too long for a second. Ivanovic stood off Naismith and he drilled in a low shot from the edge of the box.
Nemanja Matic pulled his side back into the game with a thunderous 30-yard strike but Chelsea barely threatened an equaliser.
Hazard went closest with a couple of efforts which deflected just wide of Tim Howard’s post.
Frontman Costa didn’t get a single sight of a goal as he once again lost his focus - seemingly intent on trying to rough up another opposing defence.
He caught Seamus Coleman in the face with a reckless, flailing arm while his bustling of Stones and central defensive partner Phil Jagielka got him nowhere and he was finally booked for a hack on Argentine debutant Ramiro Funes Mori.
Naismith put the game beyond doubt late on when he finished off another well-worked Everton move to slide the ball under Begovic from six yards.
It was Martinez’s second victory of the season over Chelsea - after he successfully held off their bid to prize away Stones - and the Spaniard was full of praise for his young side. “It was a great win over a team that won the league by a mile last season, but I still think we can play a lot better,” he said.
Howard 6, Coleman 7 (Fune Mori 77, 6), Stones 9, Jagielka 7, Galloway 6, McCarthy 7, Barry 7, Besic 6 (Naismith 9, 9), Barkley 7, Kone 7 (Lennon 72, 6), Lukaku 7.
Begovic 6, Ivanovic 4, Zouma 5, Terry 6, Azpilicueta 6, Mikel 5 (Kenedy 55, 6), Matic 6, Pedro 5 (Falcao 70, 5), Fabregas 5 (Willian 74, 5), Hazard 6, Costa 5.
Andre Marriner (W Midlands).