Play began around 6:30 p.m. with ninth-seeded Jelena Jankovic facing American qualifier Jessica Pegula on the Althea Gibson court by the clubhouse. Crews were drying off the main Billie Jean King Court for a pair of matches featuring 10th-seeded Jula Goerges and third-seeded Samantha Stosur.
Earlier, Andrea Petkovic withrew from the tournament because of a right calf injury, moving second-seeded Caroline Wozniacki into the quarterfinals.
DAVIS CUP: Former Georgia star John Isner will play top-ranked Novak Djokovic today in the first match of the quarterfinal between the United States and Serbia in Boise, Idaho.
Sam Querrey, the top-ranked American at No. 20, will face Viktor Troicki in the second match. The draw was announced Thursday.
The top-ranked doubles team of Bob and Mike Bryan will take on Nenad Zimonjic and Ilija Bozoljac on Saturday.
In reverse singles on Sunday, Querrey and Djokovic will play the first match followed by Isner and Troicki.