Sara Errani and Andrea Vavassori weren't even sure they would get to defend their US Open mixed doubles title. Organizers revamped the tournament because they wanted singles superstars, not doubles specialists.

The second semifinal between defending champions Sara Errani/Andrea Vavassori and the all-American, last-minute alternate pairing of Danielle Collins/Christian Harrison is underway, as they bid to join Świątek/Ruud in the mixed doubles finale.