Williams improved to 49-3 this year with a 6-1, 6-1 romp past fifth-seeded Lourdes Dominguez Lino. Williams allowed Dominguez Lino to take just 12 points in seven games serving and converted all six of her break opportunities.
She actually lost more points (19) on serve but still took nearly two-thirds of the points in the match. Williams improved to 4-0 in her career versus Dominguez Lino
All four of Friday's quarterfinals were one-sided with only one lasting more than 65 minutes.
Third-seeded Klara Zakopalova dispatched qualifier Richel Hogenkamp 6-2, 6-3 in 56 minutes. Zakopalova dropped serve twice but countered that with six breaks.
No. 8-seeded Johanna Larsson, a local favorite and the 2011 tournament runner-up, had seven breaks in a 6-1, 6-2 win over Mathilde Johansson and Flavia Pennetta took out Virginie Razzano 6-1, 6-3. Pennetta won 65 percent of the points on serve and 54 percent when receiving.
Williams next goes against Zakopalova, against whom she is 3-1 all-time. They haven't played each other since 2009, however. Pennetta was a 6-4, 6-1 winner over Larsson earlier this year in their only previous meeting.
Swim Week Miami Beach 2014 [PHOTOS]