It was a dreadful day for the favourites, with the top four seeds all going out.
Second seed Coco Vandeweghe lost 7-5 1-6 6-2 to Lesia Tsurenko, number three Elena Vesnina was beaten 7-6 (7/3) 6-4 by Natalia Vikhlyantseva and Irina-Camelia Begu beat fourth seed Anastasija Sevastova 6-4 6-3.
Kristina Mladenovic of France returns a shot against Ying-Ying Duan of China on day one of the 2017 China Open at the China National Tennis Centre on September 30, 2017 in Beijing, China
Image credit: Getty Images
Magdalena Rybarikova defeated Maria Sharapova in the first round but only lasted a set of her second-round clash with Alize Cornet before retiring injured, while sixth seed Daria Gavrilova also pulled out.
Julia Goerges was the sole seed to survive, the seventh seed beating Yulia Putintseva 6-3 6-3.
There were also upsets at the Luxembourg Open, with third seed Anett Kontaveit beaten 6-4 6-4 by Britain's Heather Watson.
Seventh seed Beatriz Haddad Maia also lost but second seed Kiki Bertens was leading Andrea Petkovic 6-2 2-1 when the German retired while fifth seed Elise Mertens recovered from losing the second set 6-0 to beat Madison Brengle.