Serena broke serve again at 3-2 to lead 4-2 following two Venus forehand errors and two backhand errors.
Serving for set one leading 5-4, Serena struck two aces out wide to lead 40-0.
Another 103 miles per hour ace out wide from Serena on set point two ended the set 6-4.
Set two stayed on serve early with Venus holding serve to lead 3-2 before Serena held serve as well to level the set at 3 all.
However with Venus serving at 15 all, Serena hit a down the line backhand winner followed by a crosscourt forehand winner to lead 15-40.
Venus reached deuce before Serena struck a crosscourt backhand winner to set up another chance to break serve.
And for all her improved fight from set one to set two, Venus hit a fatal double fault to drop her service game and trail 3-4.
Displaying the lethal combination of topspin, power and consistency that propelled her to tennis’ top ranking, Serena struck back to back aces to take a 40-0 lead in her final service game of the day.
At 40-15, Serena then powered a 121 miles per hour ace down the tee to hold serve and lead 5-3.
With Venus serving to stay in the match, Serena struck a down the line backhand winner to lead 15-0.
Venus then continued her slow fade for the day as she netted a crosscourt backhand before double-faulting to trail 0-40 and face three match points.
However one match point was all it took for Serena to power into the quarterfinals as Venus struck a crosscourt backhand long to end the match before the sisters would meet in an embrace at the net.