Acapulco - Top-seeded Sloane Stephens rallied to beat Dutch qualifier Arantxa Rus 5-7, 7-6 (6), 6-0 on Wednesday night to reach the Mexico Open quarter-finals.
Rafael Nadal withdrew before his opening match, saying he needs more time to recover from a hip injury. The second-ranked Spanish star hasn't played since retiring in the Australian Open quarter-finals.
Stephens saved a match point in the second-set tiebreaker against the left-hander. The American won the US Open last year for her first Grand Slam title and took the Acapulco hard-court event in 2016. She'll face Switzerland's Stefanie Voegele, a 6-3, 6-4 winner over Greece's Maria Sakkari.
Second-seeded Kristina Mladenovic also overcame a slow start to advance, beating Brazil's Beatriz Haddad Maia 3-6, 6-3, 7-5. Mladenovic will play seventh-seeded Lesia Tsurenko of Ukraine, a 6-3, 6-1 winner over Arina Rodionova of Australia.
Third-seeded Daria Gavrilova of Australia beat Mexico's Renata Zarazua 7-5, 6-3 to set up a match against Veronica Cepede Royg of Paraguay. Royg beat No 5 Irina-Camelia Begu of Romania 7-6 (3), 6-1.
Fourth-seeded Zhang Shuai of China faced Jil Teichmann of Switzerland in a late match.
In men's play, second-seeded Alexander Zverev beat fellow German Peter Gojowczyk 7-6 (6), 6-3. Zverev will face Ryan Harrison of the United States. Harrison edged Argentina's Diego Schwartzman 6-3, 5-7, 6-4.
Third-seeded Dominic Thiem of Austria topped Denis Shapovalov of Canada 6-2, 6-3. The Argentina Open winner two weeks ago on clay, Thiem will face the winner of a late match between sixth-seeded Juan Martin del Potro of Argentina and David Ferrer of Spain.
Results from the ATP and WTA Mexican Open on Wednesday in Acapulco (x denotes seeding):
Jared Donaldson (USA) bt Matthew Ebden (AUS) 6-3, 6-1
Chung Hyeon (KOR) bt Ernesto Escobedo (USA) 6-3, 6-1
Dominic Thiem (AUT x3) bt Denis Shapovalov (CAN) 6-2, 6-3
Ryan Harrison (USA) bt Diego Schwartzman (ARG) 6-3, 5-7, 6-4
Sloane Stephens (USA x1) bt Arantxa Rus (NED) 5-7, 7-6 (8/6), 6-0
Stefanie Vogele (SUI) bt Maria Sakkari (GRE) 6-3, 6-4
Veronica Cepede (PAR) bt Irina Begu (ROM x5) 7-6 (7/3), 6-1
Daria Gavrilova (AUS x3) bt Renata Zarazua (MEX) 7-5, 6-3
Lesia Tsurenko (UKR x7) bt Arina Rodionova (AUS) 6-3, 6-1