Both advanced to the quarterfinals in three sets.
The world No. 1 defeated Gilles Muller, 6-4, 7-5, 7-5, and hasn't lost a set yet Down Under.
The 19-year-old won 6-2, 6-4 to reach her first Grand Slam quarterfinal.
"Someone in the crowd was like, 'Come on Serena use spin!' and I was like, 'OK,'" Williams said.
The 34-year-old American won 6-3, 2-6, 6-1.
Can tennis players ever change? Tomas Berdych will try to find the answer again.
The Williams sisters' latest wins showed us the results of their relationship in microcosm.
In the podcast, we discuss the opening week of play Down Under.
Inside the first Grand Slam of the season.