San Antonio, TX, USA, 17 March 2016 | AAP/

Australian top seed Daria Gavrilova has booked her place in the quarterfinals of the WTA San Antonio Open.

Gavrilova downed Greek Maria Sakkari 4-6 7-6(5) 6-3 in just over two-and-a-half hours and next faces Alison Riske for a spot in the semis after the American upset Belgian seventh seed Kirsten Flipkens 7-5 6-1.

Sixth-seed Misaki Doi is the second-highest seeded player left in the tournament after a 7-5 7-6(4) win over Xinyun Han.

Meanwhile, Casey Dellacqua is through to the doubles semifinals.

Partnering Darija Durak, the duo beat Americans Ashley Weinhold and Caitlin Whoriskey 7-6(1) 6-1 and will next meet another Australian in Anastasia Rodionova and her Polish partner Klaudia Jans-Ignacik.