U.S. Open champion Coco Gauff fought off a challenge from Croatia's Petra Martic 7-5, 5-7, 7-6 (2) to move on to the round of 16 at the China Open in Beijing on Tuesday.
For Gauff, it was her 14th straight victory. Both Martic and Gauff pulled off six service breaks during the match, which lasted three hours. Martic had 15 chances to break Gauff's service.
The most crucial break came with Martic serving up 5-4 in the third set with a chance to put the match away, but Gauff broke her serve to tie the match at five games.
In the next round, the third-seeded Gauff will meet Russian Veronika Kudermetova, the 16th seed, who knocked out Lesia Tsurenko of Ukraine 3-6, 6-0, 6-0.
In other action, top seed Aryna Sabalenka of Belarus defeated Brit Katie Boulter 7-5, 7-6 (2), and No. 2 seed Iga Swiatek of Poland topped Varvara Gracheva of France 6-4, 6-1.
Fourth-seeded Jessica Pegula also advanced in three sets, defeating Anna Blinkova of Russia 6-7 (2), 6-2, 6-1 in her opening round. It was Pegula's first career win in Beijing.
In the round of 16, Pegula's opponent will be the 13th seed, Jelena Ostapenko of Latvia. Pegula is 3-1 against Ostapenko.
Sabalenka will face Jasmine Paolini of Italy. Swiatek will meet countrywoman Magda Linette.
The fifth seed, Elena Rybakina of Kazakhstan, eliminated Tatjana Maria of Germany 7-5, 6-0. Her opponent in the next round will be Mirra Andreeva, who beat fellow Russian Anastasia Pavlyuchenkova in straight sets.
Ukrainian Marta Kostyuk upset the seventh seed, Ons Jabeur of Tunisia, 7-6 (5), 6-1
No. 9 seed Caroline Garcia of France got past Yulia Putintseva of Kazakhstan 6-3, 3-6, 6-3, but the No. 11 seed, Daria Kasatkina of Russia, fell to China's Xinyu Wang in two sets.
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