Four-time Grand Slam champion Kim Clijsters has been taking medication for a sore right shoulder and says she’s concerned about how it will hold up during the upcoming clay court season. Clijsters said she began to take pain medication during her run to the 2011 Australian Open title.

"Nothing seriously, just like an Advil here and there, a painkiller,” said Clijsters, who edged Sara Errani 6-3, 2-6, 6-4 in the second round of Indian Wells. "I thought after this break [between the Paris Indoors and Indian Wells] I had treatment on it, while I was off, it felt fine. Just when I'm not training it feels fine. But as I got into hitting a little bit more again, it slowly just flared up a little bit. Today I just felt with those higher shots, I kind of just feel it more. I kind of feel it pinching a little bit more when I have to do that kick serve and when I have to just reach that right arm up higher with the forehand.”

The 27-year-old Clijsters will be joined by her personal osteopath when the tournament in Miami kicks off the week after next, but says that having to create more of her own pace when she begins the clay court season in early May is reason for worry.

“On hard courts I know that I am able to control it," said Clijsters, who will face Marion Bartoli in the next round. "I'm concerned for what's coming up next, and that's the clay court season. I have had my osteopath who travels with me, he's been paying close attention to it. We have been keeping it at a level where it's not getting worse. [My osteopath] is coming to Miami, so he's got some extra work to do."—Matthew Cronin