No. 86 Maria, a former Wimbledon semifinalist, toppled No. 8 Keys, who hit 10 aces but failed to get a break. Keys, the No. 2 seed, exited with the No. 1, Zheng Qinwen, who lost to No. 8 Amanda Anisimova of the U.S. 6-2, 4-6, 6-4.
Anisimova and Maria last met seven years ago.