(CNN) -- Third seed Li Na and fourth seed Jelena Jankovic have both been forced to withdraw from the Paris Indoor Open on Tuesday because of injury.
French Open champion Li was trailing Bulgarian Tsvetana Pironkova 7-6 3-2 in her first round match when calling it a day because of a back injury.
Meanwhile, Serb Jankovic pulled out before her opening match due to the thigh injury she picked up during her Fed Cup encounter against Belgian Kirsten Flipkens at the weekend.
Li, who received courtside treatment during her match, told reporters: "I hurt myself in the Fed Cup last weekend.
"It had gotten better since and this morning it didn't hurt. But the stab of pain returned, very strong and I couldn't continue. I don't know if it's because of the Fed Cup, maybe I'm getting old as well," added Li, who turns 30 later this month.
Meanwhile, Jankovic also spoke about her injury, saying: "I had hoped that after treatment I could still play here but unfortunately it's impossible.
"Australian Open, the Fed Cup and then here -- that's a lot of tennis. But it's important for me to play for my country," she added.
Australian Open finalist Maria Sharapova is the top seed for the tournament, with local favorite Marion Bartoli seeded two.