Serena Williams is set to lead the field in Madrid next week and said that she isn't really aware of the difference between court speeds.
Last year, the world No. 1 lost to Petra Kvitova on Madrid in the quarterfinals but went on to capture the Rome title, crushing Sara Errani in the final. She was then stunned by Garbine Muguruza in the second round at Roland Garros.
This year, Williams most recently played on clay at Fed Cup against Italy, winning her two singles but losing in doubles in the fifth rubber.
"I'm not sure if this is a good thing or a bad thing, but I'm never really aware of the speed of the court," said Williams, who won Roland Garros in 2002 and 2013. "My friend Caroline [Wozniacki] always jokes with me, she's like, 'I never ask you whether the court is slow or fast.' Because I just don't know. I'm so happy just to be out there. For me it's all the same. Clay is slow, grass is fast and hard is medium, and that's just how I look at it."