Serena Williams, right, will be replaced by sister Venus in Sunday’s Kastles match as she rests her back for the Olympics. (Kirsty Wigglesworth/AP)

Serena Williams will not play her scheduled match with the Washington Kastles on Sunday and will be replaced by her sister, Venus Williams, when the Kastles host Kansas City.

According to a news release, Williams withdrew from the match to further rest her back as she prepares for the Summer Olympics. Venus will fly to London after Sunday’s match to join her sister as they go for a third gold medal in women’s doubles.

Serena will also represent the United States in singles competition. She has never won an Olympics singles title and is considered the favorite after beating Agnieszka Radwanska to win her fifth Wimbledon championship earlier this month.

“After winning Wimbledon and Stanford, I need to rest my back,” Serena said in a statement. “I’m disappointed that I won’t be able to see my D.C. fans, but can’t wait to go for gold in London.”

Venus played with the Kastles on Sunday night as they topped visiting Boston to remain undefeated. Along with this Sunday’s match, Venus was already scheduled to join the team on Saturday night as they travel to New York to face the Sportimes.

“I can’t think of a more fitting place than D.C., our nation’s capital, to play my last match before representing Team USA,” Venus said in a statement.