Veteran U.S. star Venus Williams will rejoin Washington as the Kastles bid to successfully defend their World Team Tennis title on championship weekend Sept. 14-16 in Charleston, S.C. (Matt McClain/For The Washington Post)

The Washington Kastles’ 30-match winning streak and pursuit of a second straight league title received a boost on Thursday as the team announced that Venus Williams will return for September’s championship weekend.

Williams played three matches in July with the Kastles before leaving for the Olympics in London, where she teamed with younger sister, Serena, to win gold in women’s doubles. The pair earlier won doubles at Wimbledon.

The World Team Tennis semifinals and finals will be held Sept. 14-16 in Charleston, S.C. The Kastles will meet the New York Sportimes, led by John McEnroe. The winner will advance to the final against the winner of Orange County and Sacramento.

Williams helped the team remain undefeated with a come-from-behind win against host New York on July 21.

The Kastles entered the final set trailing by six games before Williams topped Martina Hingis, 5-1, and won both overtime games and all seven points of the super tiebreaker to give the Kastles a 21-20 win.

In last year’s final, the Kastles topped the St. Louis Aces, 23-19. It completed the first undefeated season in the history of the league. The Kastles haven’t lost a match since July of 2010.

Along with Williams, the Kastles will have league men’s MVP Bobby Reynolds, top doubles player Leander Paes and sisters Anastasia and Arina Rodionova. Paes and Anastasia Rodionova both played doubles in the Olympics; Paes with India and Rodionova with Australia. Paes advanced to the second round, while Rodionova fell in the first.

— Matt Breen