Petra Kvitova withdrew from the French Open on Monday due to an injury to her forearm, hours before her first match at the tournament against Romania's Sorana Cirstea.
"I'm so disappointed to have to announce my withdrawal from Roland Garros," the sixth seed said on Twitter.
"I've had pain in my left forearm for a few weeks and last night an MRI confirmed a grade two tear which could unfortunately could get a lot worse if I play today.
The Czech player has been replaced in the draw by lucky loser Kaja Juvan of Slovenia.
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)