Defending French Open champion Garbine Muguruza survived a scare to beat world number 99 Anett Kontaveit 6-7 (4-7) 6-4 6-2 and reach the third round.
The fourth seed was a set and a break down but recovered to win in two hours and eight minutes.
The 23-year-old will now play Yulia Putintseva, seeded 27.
The women's draw is wide open, especially after world number one Angelique Kerber and British hope Johanna Konta went out in round one.
Watched by sister Serena - who will not play again this season because of her pregnancy - Venus Williams easily beat Kurumi Nara 6-3 6-1 to move into round three for the first time in five years.