Barbora Krejcikova's French Open campaign came to a premature end after the reigning singles and doubles champion said she had to withdraw from the Grand Slam following a positive test for COVID-19 on Wednesday.

Krejcikova, who returned to action at Roland Garros from an elbow injury that had sidelined her since February, was knocked out in the first round of the singles in which she was the second seed, losing to Frenchwoman Diane Parry in three sets.

Czech Krejcikova had been due to start her doubles campaign along with compatriot Katerina Siniakova.

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"Last night I started to feel bad and this morning I woke up with fever. I decided to get tested for COVID and it came back positive," Krejcikova wrote on Instagram.

"I am extremely sad I won't be able to defend my title in doubles here, but on the positive side I am glad I am injury free and can't wait to get healthy and back to training."

Another Czech player, Marie Bouzkova, was also forced to withdraw from Roland Garros after testing positive for the virus.

Bouzkova had been due to face Elise Mertens in the second round and she did not play her first-round doubles match either.

"Unfortunately, I tested positive for COVID today for the first time, so I am withdrawing from both singles and doubles here in Paris," she wrote on Twitter