U.S. Open champion Sloane Stephens and runner-up Madison Keys were knocked out of the Wuhan Open in the first round on Monday.
In their first matches since the final at Flushing Meadows, the 17th-ranked Stephens lost to Wang Qiang of China 6-2, 6-2, while the 12th-ranked Keys was beaten by Varvara Lepchenko of the U.S. 6-2, 7-6 (4).
Stephens' serve was broken early in both sets. Wang closed out the victory on her sixth match point.
Keys, seeded 10th, broke Lepchenko early in the second set, but the qualifier rebounded. Lepchenko was broken while serving for the match at 6-5 but rushed to 5-1 in the tiebreaker.
They weren't the only upsets.
Seeds No. 5 Johanna Konta and No. 12 Angelique Kerber, and former U.S. Open champion Sam Stosur were also sent packing.
Konta lost to Ashleigh Barty of Australia 6-0, 4-6, 7-6 (3) in the second round, and Kerber lost her opener to Caroline Garcia of Spain 3-6, 6-3, 6-1. Stosur fell to Swiss wild card Jill Teichmann 6-4, 3-6, 6-3.
Konta, who occupies the last spot in the Race to Dubai, served for the match, but Barty broke back to force the tiebreaker and earned her career-best win. Konta has lost her last four matches.
Garcia dropped the first set to Kerber but asserted control from there, to the point she led 5-0 in the third set.
Also advancing were Agnieszka Radwanska, Lauren Davis of the U.S., Barbora Strycova of the Czech Republic, Alize Cornet of France and Kiki Bertens of the Netherlands.