Djokovic led 4-2 during a tight first set against Dominic Thiem, but dropped the third 6-0 in a surprisingly one-sided defeat to the 23-year-old Austrian.
"I play a great match or two in a row, and then I play a completely opposite match,” he told reporters after the match. “That’s what happened.”
The 12-time Grand Slam champion added that he was having "technical problems" with several parts of his game.
"I obviously always expect a lot from myself, but it's a fact that I'm not playing close to my best, and I know that,” he said. "Again, I'm trying, as everyone else, to work on the game and, you know, work on things. Sometimes it works, sometimes it doesn't."
Djokovic, who won the 2016 French Open to get his fourth Grand Slam victory in a row, now holds none of the four majors. Having fallen to No. 2 in the rankings, he will be No. 3 or No. 4 following the tournament. But he insists he is fully motivated to get back to the top.
"You know, it's one of the highest points that you can reach as a tennis player, is to be No. 1,” he said. “And, of course, one of the highest goals of any player. You know, I was very fortunate, obviously, to spend a lot of time there. It’s more about the game itself—my own game, you know—working on it, because obviously there are things that need to be better and I need that continuity.
"I'm going to focus on that, and then I guess results will follow, and No. 1 ranking, as well. Then I will have a better chance if I start playing better.''
But at the moment, he isn't sure what to do. The 30-year-old also recently stopped working with his coaching team, and has added Andre Agassi as a part-time coach. He is also looking for another full-time coach.
Djokovic said he might add a warm-up event to his schedule before Wimbledon, something he doesn't normally do, but had not decided. The Serb even indicated he is considering taking a break from the game.
"I'm thinking about many things," said Djokovic. "You know, I'm just trying to sense what's the best thing for me now. Obviously there has been a lot of changes with the team and so forth. [I am] so excited to work with Andre and the new team. At the same time, I have [a] responsibility to the game itself, towards others.
"Obviously it's not an easy decision to make, but I will see how I feel after Roland Garros and then decide what to do next."
Djokovic has not won a tournament since the beginning of the season, defeating Andy Murray in the final in Doha.
Holding Serve with Roger Federer will air on Thursday, June 8th at 2 p.m. ET, only on Tennis Channel.
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