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.

Sara Errani and Andrea Vavassori defended their U.S. Open mixed doubles title Wednesday night, keeping a traditional team on top of a revamped event filled with singles stars. The Italians beat No.