Caroline Wozniacki and Eugenie Bouchard have withdrawn from their respective tournaments on the eve of Roland Garros.
On Tuesday, Wozniacki was a set down in opening round match at the Internationaux de Strasbourg – where she was the top seed – before she withdrew, citing back issues.
"I felt it kind of in the middle of the first set," the former world number one told BBC Sport.
"At this point, I think it's important for me to try and get ready for the French Open and be 100% for that."
Meanwhile, Bouchard withdrew from the Nuernberger Cup without playing after rolling her ankle.
"It's a great tournament for me with lots of great memories," said the Canadian.
"I'm sorry I cannot see the fans this year and hope to be back next year."
Roland Garros begins on Sunday in Paris.