Russell Wilson and Ciara were seen at the U.S. Open sitting in Serena Williams' box at Arthur Ashe Stadium in New York City.

The couple, along with a host of other celebs, cheered on Serena Williams as she played Ajla Toljanovic.

US open

The third-round match was lost by Serena. This is most likely her final match.

Russell Wilson and Other Stars

Ciara sent it a day later to her friend, Serena Williams. It was a privilege to be part of your amazing journey.

The Goat, Icon, and Best Competitor. The Blue Print. Best Mommy. We love you so much!"

Russell Wilson and Other Stars

Serena, mother to 5-year-old daughter Alexis Olympia Ohanian Jr. wrote last month in a Vogue essay that

she intends to quit tennis and that she and her husband Alexis Ohanian are trying to have another child.

After her U.S. Open defeat, Serena said that she was ready to "like, be a mother, explore a new Serena."