Spain’s Paula Badosa cast fresh doubts about her fitness heading into the clay-court season after the former world No. 2 pulled out of this month’s Charleston Open with a lower back injury and did not provide a timeline for her return.

Badosa had fallen out of the world’s top 50 rankings due to a string of injuries, including a chronic lower back issue that made her consider retirement last year, but the 27-year-old reached her first Grand Slam semifinal at the Australian Open in January.

She then quit midway through her Merida quarterfinal with Daria Saville and skipped Indian Wells before aggravating the problem again and pulling out of the Miami Open on Monday following a third-round win over Clara Tauson.

“Hello everyone, as you know I had to withdraw from Miami and the upcoming tournaments,” the world No. 11 said on Instagram after the Charleston Open confirmed she had pulled out.

“It’s very sad and tough to deal with the pain … stopping and coming back every single time.

“Now it’s time to go through the recovery process again. Hopefully I will be back soon.”

The Charleston Open will run from March 31-April 6 before several high-profile clay-court tournaments next month leading up to the French Open beginning in late May.