Simona Halep was troubled by injury in a loss to Dominika Cibulkova, while Caroline Garcia was beaten by Katerina Siniakova in Wuhan.
The Wuhan Open began with Kiki Bertens overcoming a hectic 24 hours and Garbine Muguruza earning a measure of revenge.
Naomi Osaka proved a hugely popular winner after thrashing Dominika Cibulkova in Tokyo on Wednesday.
A tricky first-round test was well negotiated by Garbine Muguruza at the Tokyo Open, where Naomi Osaka will face Dominika Cibulkova.
Two-time grand slam champion Garbine Muguruza bowed out of the US Open in the second round.
Simona Halep became the first top-seeded woman to lose in the opening round of the US Open.
Simona Halep was leading 4-3 and 30-15 in the final set against Alja Tomljanovic when rain washed out play on Wednesday.
Garbine Muguruza telah menarik diri daripada saingan Piala Rogers selepas gagal pulih daripada masalah kecederaan lengan yang telah menghalangnya daripada beraksi di Silicon Valley Classic.
The arm injury that kept Garbine Muguruza out of the Silicon Valley Classic has now prevented her from competing in the Rogers Cup.
After crushing Serena Williams, Johanna Konta cruised past Sofia Kenin 6-1 6-4 in San Jose on Wednesday.