Thats what Andrea wrote in her Indian Wells blog about the practice:
This past week I got to practice with a tennis legend, Steffi Graf! So many reporters in Germany have asked me if I ever have met her, but this was the first time, and it was incredible. She has an injury right now, so she could only play for 45 minutes, but it was amazing and intense. I swear that right now, if she played again, she would be top 30 in the world. She was hitting amazing, full power, and I was totally playing so hard so I wouldn’t tank. I was dying after 45 minutes, with no breaks, it was such a tough practice! What an amazing experience to practice with her, I won’t ever forget it.
I didn’t get to see her play during her prime years when I was growing up, because I was so young, but I love watching some of the old matches on YouTube. It’s fun to watch players from the past like Sabatini, Capriati, and Graf, and see how they played. There is a lot that can be learned from them.