Tennis fans have been left gutted after Kim Clijsters suffered a major setback in her return to professional tennis.
The former World No.1, who was due to return to competition in 10 days in Miami, announced she'd pulled out of the tournament on Sunday.
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The 37-year-old from Belgium, who won the Miami tournament in 2005 and 2010, had been handed a wild card to take part in her first official match since last year's US Open.
In September she she lost to to Ekaterina Alexandrova in the first round at Flushing Meadows.
The four-time major winner then underwent a knee operation in October and contracted COVID-19 in January, forcing her to revise her plans.
"While the symptoms were mild it did disrupt my training schedule," the mother of three announced on Twitter.
"Unfortunately I am not where I need to be especially if I want to compete with the best."
However Clijsters assured fans she's not on the verge of quitting.
"It's disappointing and frustrating," she said.
"I knew this was going to be hard when I started this journey - and there have been challenges outside my control.
"I'm not ready to quit... I'm going to keep pushing and see what's possible."
Fans were left gutted by the news.
Kim Clijsters' third comeback to pro tennis
Clijsters first retired from tennis in 2007, taking a break to have the first of her three children.
She returned to the sport in 2009 and won the US Open for a second time as an unseeded wildcard in her third tournament back.
The Belgian won her third Flushing Meadows title in 2010 followed by an Australian Open the following season, before retiring again in 2012.
She only played three tournaments and three matches in 2020, beaten each time in the first round.
Currently ranked 1055 in the world, Clijsters had also been offered a wildcard at Charleston.
She has 43 singles titles, including three US Open titles and one Australian Open.
She has also won the WTA Championships three times as well as the Fed Cup with her compatriot Justine Henin.