World number four Dominic Thiem said he is not yet fully fit and is skipping this month's ATP Masters 1000 event in Monaco.
The U.S. Open champion opted out of the ongoing Miami Masters and has not played since making an early exit at the ATP 500 event in Dubai last month.
The 27-year-old had targeted the European claycourt season to return after struggling with a foot problem recently.
"After Doha and Dubai I needed a break," Thiem said on his website "I'm not at 100% yet. I'm so sorry, I would have loved to play in Monte Carlo, but it won't work out."
Thiem, who won his maiden Grand Slam title at Flushing Meadows last year, began the 2021 season with one win in two matches at the ATP Cup before exiting the Australian Open in the fourth round.
After Melbourne, his desert swing also ended in disappointment with defeat to South African qualifier Lloyd Harris in his opening match in Dubai, which came after a quarter-final exit in Doha last week.
Thiem said he will be practising on clay at home in Austria during the Monte Carlo event.
"I'm having tough weeks ahead of me, I have a lot of work to do," he added.
(Reporting by Sudipto Ganguly in Mumbai; editing by Peter Rutherford)
