India, Sept. 13 -- On Wednesday evening, Aryna Sabalenka watched from the practice arena as Elena Rybakina ended her 99-week reign as the WTA world No. 1. Rybakina sealed the top ranking by beating the resurgent Qinwen Zheng to reach her first US Open semi-final.

Sabalenka, already through to the last four, paused during her training and looked over towards the proceedings at Arthur Ashe Stadium, perhaps on a television. Her disappointed expression lasted a moment before she turned back to her practice.

The threat to the world No. 1 ranking had been looming for some time. Rybakina's ascent had been building since last season, when she ended 2025 by beating Sabalenka in the WTA Finals Riyadh championship match. Weeks later, she came back...