Stan Wawrinka will play no part in this month's ATP Masters series tournaments at Indian Wells and Miami as he continues his recovery from knee surgery.
The 32-year-old was forced to miss the second half of last season after undergoing a knee operation following a first-round exit at Wimbledon in June.
Wawrinka returned to the circuit at the Australian Open but has struggled for form and suffered an opening-round exit to world No 259 Tallon Griekspoor in Rotterdam, before being forced to withdraw against world No 193 Ilya Ivashka in Marseille.
The world No 12 had shown encouraging signs of a return to form with a run to the semi-finals in Sofia last month, but Wawrinka hopes a period of recuperation will aid his return to full fitness.
"Unfortunately I need to announce that I won't be able to play in Indian Wells and Miami," Wawrinka said.
"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, a three-time Grand Slam champion, has targeted a return in time for the clay court campaign, which - for the sport's biggest players - begins with the Monte-Carlo Masters in April.
"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," he said.
"I love that part of the season and hope to be ready by then."
You can watch the Tie Break Tens tournament live from Madison Square Gardens in New York on Sky Sports Main Event and Sky Sports Mix from midnight on Monday, and don't forget you can watch repeats on Sky Sports Action from midday on Tuesday and 7pm on Sky Sports Action & Sky Sports Mix.
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