Stan Wawrinka will not play at Indian Wells or in the Miami Open to give himself every chance of being fully fit for the clay-court season.
The three-time grand slam champion underwent knee surgery last year and has struggled since returning in 2018.
Wawrinka withdrew from the Open 13 Marseille last month after being troubled by his left knee during a match against Ilya Ivashka.
The Swiss on Thursday decided to pull out of the Indian Wells Masters, which starts next week, and the Miami Open - bringing an end to his hard-court season.
He said: "Unfortunately I need to announce that I won't be able to play in Indian Wells and Miami.
"They are both amazing events, but coming back from a big surgery is complicated and after having played a few tournaments, I have discussed with my team that it is best for me to build on the progress and go back to practice.
"I've enjoyed being back on tour playing matches and this gives me even more motivation to go back on the practice court. My goal is to find my highest level again and in order to do that I will keep working hard every single day."
Wawrinka added: "I need to be patient and give my body the time it needs, but as of now my goal is to come back on clay.
"I love that part of the season and hope to be ready by then. I want to thank all my fans, who are always a great support. I'm working hard on and off the court and hope to be back within a few weeks."