(Photo credit: Robert Deutsch-USA TODAY Sports)

Madison Keys stumbled in her first match after reaching the U.S. Open semifinals, falling 6-2, 7-6 (5) in an all-U.S. second-round matchup at the Guadalajara (Mexico) Open Akron on Tuesday.

Keys, the tournament's fourth seed, received a first-round bye.

Navarro converted five of her seven break-point opportunities, while Keys broke serve three times on five chances.

Navarro advances to face former U.S. Open finalist Leylah Fernandez of Canada, who knocked out 13th-seeded Elise Mertens of Belgium 6-3, 6-4.

The event's top two seeds cruised to wins, as No. 1 Ons Jabeur of Tunisia routed the United States' Alycia Parks 6-2, 6-2, and No. 2 Maria Sakkari of Greece downed Australia's Storm Hunter 6-2, 6-4.

Third-seeded Caroline Garcia of France came from behind to beat Belarus' Aliaksandra Sasnovich 4-6, 7-6 (5), 6-4, and eighth-seeded Ekaterina Alexandrova of Russia eked out a 7-6 (5), 7-6 (8) victory over Poland's Magdalena Frech.

The United States' Sofia Kenin eliminated 12th-seeded Anhelina Kalinina of Ukraine 6-2, 7-6 (5).

Guangzhou Open

No. 4 seed Lucia Bronzetti of Italy swept past Ya Yi Yang of Taiwan 6-1, 6-0 in an hour flat in first-round action in Guangzhou, China.

Bronzetti broke Yang's serve five times in nine opportunities and won 21 of 27 first-service points while never losing her own serve. Her next opponent will be Japan's Moyuka Uchijima, who outlasted France's Jessika Ponchet 7-5, 3-6, 6-3.

No. 3 seed Tatjana Maria of Germany also had an easy time in the first round, beat Alexandra Eala of the Philippines 6-3, 6-0.

Daria Saville of Australia rallied past Germany's Anna-Lena Friedsam 3-6, 6-3, 6-1, and Viktoria Hruncakova of Slovakia beat Russian Anna Kalinskaya 7-6 (4), 3-6, 6-3. Other first-round winners included Viktorija Golubic of Switzerland; Yulia Putintseva of Kazakhstan; and Xiyu Wang, Yue Yuan and Zhuoxuan Bai of China.