Hilary Swift for The New York Times
Youth ruled tennis on Friday in Shanghai, where Stefanos Tsitsipas upset No. 1 Novak Djokovic and Alexander Zverev beat his new mentor, Roger Federer.
It also ruled a continent away in Linz, Austria, where the 15-year-old Coco Gauff added another exclamation point to her breakthrough season by defeating top-seeded Kiki Bertens, 7-6 (1), 6-4, to reach her first WTA tour singles semifinal.
“It’s my biggest win, ever,” said Gauff, sounding like a veteran surveying a long career instead of a teenager who has yet to play a full year on tour.