Beyonce told Serena Williams to dance and the tennis champion let loose.

Top-ranked Williams recounted Sunday how she came to have a part in the singer's video, "Lemonade."

Williams says, "I have known the director since I was like nine years old. I know Beyonce pretty well, so they were like, 'We would love for you to be in this particular song. It's about strength and it's about courage and that's what we see you as.'"

Williams' appearance came on the song "Sorry," which features Beyonce showing her man the stupidity of his cheating ways.

Williams says, "She told me that she just wants me to dance, like just be really free and just dance like nobody's looking and go all out. So that wasn't easy in the beginning, but then it got easier. ... I thought that particular song on the visual album was really a strong song, and it was also really fun at the same time."