Reigning Australian Open champion Angelique Kerber and last week's Indian Wells winner Victoria Azarenka, who each upset world number one Serena Williams in the final to win those titles, reached the last 16 on the women's side.
German second seed Kerber advanced 1-6, 6-2, 3-0 when 108th-ranked Dutch qualifier Kiki Bertens retired due to illness.
"I was not finding a rhythm at the beginning of the match," Kerber said. "I had to stay strong, believe and keep fighting. I hope she gets well soon but I'm glad to be in the next round."
Kerber next faces Hungary's 49th-ranked Timea Babos, who ousted 18-year-old Japanese 104th-ranked wildcard Naomi Osaka 7-5, 6-0.
Eighth-ranked Azarenka, a 26-year-old from Belrus who won 2009 and 2011 Miami titles, eliminated Polish qualifier Magda Linette 6-3, 6-0.    ?AFP