Paris - Injury-plagued former US Open champion Juan Martin del Potro admitted on Thursday that he still cannot pinpoint a return to the tour after undergoing a fourth wrist operation.
The 26-year-old del Argentine has played in just two tournaments in 2015 after managing only four in 2014 while his world ranking has plummeted to 570.
Del Potro underwent his latest wrist surgery in March.
"The hardest moments of my career are gone, those in which I didn't know what I would do next," Del Potro, who parted ways with long-time coach Franco Davin last week, wrote on Facebook.
"I've already told you the discomfort of being unable to do what I like and the suffering of watching tennis on TV. Today is a different story. I have great expectations for a new stage that began this week.
"Today I am more committed than ever to trying to come back. No more doubts or question marks. A new career for me starts today."
The 2009 US Open champion added: "This week I began rehab and did some light workout. While I start from scratch, I've been on a diet to maintain weight.
"I don't know how long it will take, I do not know at what level I will play, but I hope to be with you on the tour again."