Novak Djokovic said on Wednesday his confidence had been rocked by a string of poor results after a premature return from elbow surgery but the former world No.1 vowed to work hard to get back to winning ways.
Having exchanged a few shots with a young prospect after an intense training session in searing heat at his own tennis complex in central Belgrade, the 30-year old Serb conceded that the last 18 months have been testing.
"I have always believed in myself and that's why I was able to make all my childhood dreams come true, but right now my confidence is not at the highest level," he told reporters.
"That's not surprising given the lack of results and all I can do is knuckle down to hard work to restore it. A few good matches and one good tournament and it will come back."
Djokovic's slump began after he won his maiden French Open title in June 2016 to complete a career slam and amass 12 major honours.
A string of below-par performances were followed by Djokovic having to retire against Czech Tomas Berdych in last year's Wimbledon quarter-finals with an elbow injury which kept him sidelined until January's Australian Open.
After a last 16 defeat by South Korean upstart Hyeon Chung in Melbourne, Djokovic had another spell on the sidelines following elbow surgery and said he had come back too early because he was hungry to play again.
Since returning he has suffered early exits in Barcelona, Monte Carlo, Miami and Indian Wells.
"That was my decision because I missed playing tennis so much but I was not ready and it backfired," he said.
"After everything I have been through in the past year or so, I have had to lower my expectations but my motivation and my ambitions remain unchanged.
"After this year's Australian Open I wasn't sure whether I'd have elbow surgery or not. I was reluctant but then I realised it was the best long-term solution.
"The recent results have not been what we are used to but coming back is a process and all I can do now is knuckle down to some hard work."
Djokovic rubbished suggestions made by several local nutritionists, who were quoted by Belgrade media in recent weeks, that his meat-free diet was hampering his fitness.
"I don't want to elaborate because people have been twisting facts in the past two years and all I'll say is that I reckon I know what's best for me as an athlete and a person," he said.