Novak Djokovic raised questions over his participation in both the French Open and Wimbledon as he admitted he would not be able to play tennis for "some time" because of a wrist injury.
The Serbian was struggling with the problem as he lost to Roger Federer in the semi-finals of the Monte Carlo Masters on Saturday and afterwards conceded he needed to take a break from the sport.
The six-time grand slam winner said he would not be having surgery, but could not put a timescale on how long he would be out for.
Any lengthy absence will raise doubts as to whether or not he will be able to play the French, which starts on May 25, and Wimbledon, from June 30.
"The good thing is I don't need to have surgery," the 26-year-old told the ATP's official website.
"I don't have anything ruptured or something like that. I'm going to go see doctors tonight and then tomorrow again have another MRI.
"I really don't know what's the diagnosis, to be honest. I just rest now. I cannot play tennis for some time. How long, I don't know.
"It's really not in my hands anymore. I'm going to rest and see when it can heal 100 per cent, then I will be back on the court."
Djokovic suffered the injury in training between winning the Sony Open in Miami and heading to Monte Carlo.
He added: "The pain was there every single day from 10 days ago. At some stages it was very painful. Between the first and second match I had a day off so I didn't practise at all and I healed a little bit. Then again I started playing.
"I had two weeks between Miami and Monte Carlo. It's not like I was tired or I had some long trips or something like that. It just happened during the practice week. Sometimes it just happens. It's not predictable."