Cape Town - Chelsea's Eden Hazard cannot explain why he is struggling for his club this season.
Hazard also backed his manager's decision to to drop him from the starting line-up as he is in the "worst form of his life".
The Belgium was the Premier League's best player last season as Chelsea cruised to the title, but paid the price for his stunning fall from grace this term when Mourinho dropped him from the starting line-up for the Champions League defeat by Porto on Sept. 29.
Hazard has no goals and just two assists in 11 appearances for the club this season, a slump that has contributed to Chelsea's slide down the table, where they currently sit in 16th place.
"This is the first time in my career that I have had such a difficult spell like this," Hazard was quoted as saying by the British and Belgian media.
"I can't really explain it. All I know is that I will need to work hard in order to bounce back. At Chelsea we have concerns both as a team and individually," the 24-year-old winger added.
Hazard admitted his poor performances meant he was no longer "untouchable" as one of the first names on Mourinho's team sheet, but praised the Portuguese and backed himself to bounce back when the league resumes on October 17 after the international break.
"I was left on the bench against Porto in the Champions League, and I am no longer immune to being left out. You can be untouchable when you play well, and that has not been the case with me," Hazard said.
"I think the manager wanted to send me a message by making me a sub. I don't read everything he says, but he explains everything.
"I am not too worried for him - Mourinho is the best coach in the world when it comes to dealing with pressure. I am an optimist, and I know I can learn a lot from tough spells.
"I hope to come back stronger, and I am ready to play and do my best," he added.