MADRID, Spain – No.4 seed Victoria Azarenka has joined the Mutua Madrid Open casualty list, pulling out of her third-round meeting with Louisa Chirico because of a back injury.

Following the exits of Agnieszka Radwanska, Angelique Kerber and Garbiñe Muguruza, Azarenka was the highest seed left in the draw. However, after aggravating her lower back during morning practice the Belarusian elected to err on the side of caution.

“Unfortunately in my first match I think I tweaked my back a little bit. It was really cold, and, I don’t know, I think it’s much easier to get a little bit hurt when it’s that cold,” Azarenka said during a press conference. “And the second match obviously I was in a lot of discomfort. Having a day off I thought it was going to get better. Today before my warm-up it did feel better, but once I started hitting it came back.

“I don’t feel that I’m able to compete today. I’m just trying to make the smart decision and see the big picture.”

Azarenka’s now faces a race against time to be fit for next week’s Internazionali BNL d’Italia – her last chance to fine-tune her clay court game ahead of the French Open.

“We’ll see how it goes. Really going to take it day by day and make sure my body is ready,” she said when asked about her chances of playing in the Italian capital. “I don’t know. I don’t really have a particular answer why it happened. There could have been couple of things. I was really sick the week before that.

“I’m just trying to make the test, make sure there is nothing serious, and try to treat it as best as possible. My plan is to be ready for Rome, so hopefully I’ll be able to do that.”

Chirico, the youngest player remaining in the tournament, advances to her first quarterfinal at a WTA Premier event where she will face fellow surprise package, Daria Gavrilova.