Kessler had never defeated a top-50 opponent in her career before taking down Wang, who coughed up a 2-0 lead in the second set. Kessler also put together a strong finish, winning the final four games of the third set after Wang drew even at 2.

Despite losing, Wang still managed to finish with more aces (5-4) and fewer double faults (4-3).

Two other seeded players fell, as the Netherlands' Arantxa Rus beat Bulgarian seventh seed Viktoriya Tomova 6-3, 6-3 and France's Clara Burel got past eighth-seeded Sophia Kenin of the United States 6-4, 6-3.

Top seed Beatriz Haddad Maia of Brazil, No. 3 seed Katerina Siniakova of the Czech Republic, No. 5 seed Russian Anastasia Potapova and No. 6 seed Peyton Stearns of the United States all prevailed. Romania's Ana Bogdan also advanced.

No. 7 seed Yue Yuan of China cruised to a 6-4, 6-1 win over Croatian Petra Martic in second-round action in Monterrey, Mexico.

Yuan finished with just one ace to Martic's five but saved 4 of 6 break points and converted 5 of 6.

Fifth-seeded Elina Svitolina of Ukraine and sixth-seeded Linda Noskova of the Czech Republic also advanced with straight-set wins.

New Zealand's Lulu Sun saved a match point late in the third set and emerged with a 6-3, 2-6, 7-6 (2) win over Argentina's Maria Lourdes Carle.

--Reuters--