Barty continues to look every bit the heavy favorite as she steamrolled Italian qualifier Lucia Bronzetti 6-1, 6-1.
She has not been broken in her past five matches, having held 48 consecutive times and dropped just three points on her first serve against the Italian.
"Just continually trying to make (my serve) a weapon", she said following the emphatic win. "I'm not the biggest girl out there, but I know i've got a solid technique and I know if I can get my rhythm right and use it effectively, it can be a weapon."
Osaka remains on course for a fourth-round showdown with the world number one, easing past Madison Brengle 6-0, 6-4 behind 35 winners.
"I returned pretty well. That's not my usual stat, but i've really been working on it during the offseason, so i'm really glad it came in handy today.
"I feel like if I compare myself to the past then i'll never be satisfied. I'm just trying to take it one day at a time."
Krejcikova dominated Xiyu Wang 6-2, 6-3, forcing the Chinese into 30 unforced errors.
15th seed Elina Svitolina won when Harmony Tan retired with the scoreline at 3-6, 7-5, 6-1, setting up a blockbuster third-round match with 24th seed Victoria Azarenka, who blasted Jil Teichmann 6-1, 6-2.
30th seed Camila Giorgi knocked off Tereza Martincova 6-2, 7-6 (2) while Nuria Parrizas Diaz received a walk over from Maryna Zanevska.
Madison Keys continued her red-hot start to the season, easing past Jaqueline Cristian 6-2, 7-5. Next up for the American is Qiang Wang, who rallied from a set down to knock off Alison Van Uytvanck 2-6, 7-6 (5), 6-3.