Jelena Ostapenko faces Petra Martic’s younger sister, Petra Stakusic, in the WTA Guadalajara quarterfinals on Thursday. Ostapenko, the 2017 French Open champion, is seeded third in the tournament. She has won all three of her matches so far, dropping just five games. Stakusic, ranked 118th in the world, upset fourth seed Paula Badosa in the second round. The 21-year-old Croatian has also defeated qualifier Anastasia Gasanova and eighth seed Anastasia Pavlyuchenkova in straight sets. Ostapenko leads the head-to-head 1-0, having won their only previous meeting in 2018. The Latvian is expected to advance to the semifinals.