Among the many famous moments in Beyoncé's Lemonade album was a surprise cameo from tennis player Serena Williams. In a recent interview with WSJ Magazine, she talked about what it was like to be on the set of the famous "Sorry" video. “I’ve known Bey for a long time,” she said. And accordingly, she was a good friend by keeping the album a secret. “If you tell me, ‘Don’t say anything,’ I won’t say anything,” she said. Her friend Caroline Wozniacki confirmed to WSJ Magazine that she had no idea about the album. Williams also talked about one unexpected consequence of the filming. “I got really sore from dancing!” she recalled. And who can blame her after all that twerking? In an interview in Rome last month, Williams spoke about why she appeared on the visual album. Bey's team told her, "It’s about strength and it’s about courage and that’s what we see you as," she said. And apparently, it was also about dancing her butt off.