What happened: Serena and Venus Williams most recently played together in Cincinnati after withdrawing from Wimbledon doubles. Serena Williams and Carlos Alcaraz exited the US Open mixed doubles before the women's entry was announced.
Why it matters: The entry gives Serena another event in New York while Venus prepares for her 26th US Open singles main draw. The sisters have won each of the four major doubles tournaments at least twice.
By the numbers: The Williams sisters have won 14 major doubles titles and three Olympic gold medals together.
What to watch: The women's doubles draw will determine their opening-round opponents.