Defending champion Serena Williams will face Maria Sharapova in the Australian Open quarter-finals after both won their last-16 matches on Sunday.
Top seed Williams, who beat Sharapova in last year's final, crushed Margarita Gasparyan 6-2 6-1 in 55 minutes.
The 34-year-old American is chasing her 22nd Grand Slam title and seventh in Melbourne.
Sharapova, the 2008 champion from Russia, hit 21 aces as she battled to a 7-5 7-5 win over Swiss Belinda Bencic.
Fourth seed Agnieszka Radwanska came through a dramatic match against non-seeded Anna-Lena Friedsam 7-6 (8-6) 1-6 7-5.