(Photo credit: Robert Deutsch-Imagn Images)

Friday was a day for the underdogs in Sao Paulo, as all four lower-seeded players vanquished their foes in the quarterfinal matches of the SP Open.

Mexican fifth seed Renata Zarazua, who sent Madison Keys home in first round of the U.S. Open last month, knocked off top-seeded Brazilian hopeful Beatriz Haddad Maia, 7-6 (5), 6-3 in a two-hour, 15-minute match. Zarazua rallied from a 5-3 deficit in the first set and a 5-4 disadvantage in the tiebreaker to capture the first set, then broke Haddad Maia in the penultimate game of the match to prevail.

Unseeded Indonesian upstart Janice Tjen surprised the Philippines' No. 3 seed Alexandra Eala, 6-4, 6-1; No. 6 Francesca Jones of Great Britain took out No. 2 Solana Sierra of Argentina, 6-3, 6-4; and unseeded Frenchwoman Tiantsoa Rakotomanga Rajaonah eliminated Hungary's No. 8 seed Panna Udvardy, 6-2, 6-4.

Tjen saved both break points she faced and was a perfect 12-for-12 against Eala on second returns. She will face Jones in the Saturday's semifinals, while Zarazua takes on Rakotomanga Rajaonah.

Guadalajara Open Akron

In a match that was suspended Thursday night, Canadian Marina Stakusic ousted No. 3 Latvian Jelena Ostapenko, 6-4, 6-7 (6), 6-2 on Friday in Mexico.

Stakusic, 20, ranked 155th in the world, raced out to a 4-0 lead in the deciding set, winning 17 of the first 19 points played. She took advantage of 13 double faults by Ostapenko and converted 5 of 6 break chances.

France's Elsa Jacquemot upended sixth-seeded German Tatjana Maria 3-6, 6-4, 6-4 in the first quarterfinal match, with three more to come. Stakusic will come back Friday evening and play Colombia's Emiliana Arango in a quarterfinal encounter.

--Field Level Media