Golubic, a qualifier ranked 129th, won nearly 80 per cent of her first-serve points and did not concede a single break point in Thursday's clash.

She broke Garcia's serve five times to set up a meeting with unseeded Belgian player Greet Minnen, who beat eighth-seeded Russian Arantxa Rus 4-6 6-2 6-3 in another upset.

Fourth-seeded Kristina Mladenovic - Garcia's doubles partner when they won the Fed Cup final in a decisive match two years ago - advanced 6-4 6-2 against Margarita Gasparyan, breaking her Russian opponent's serve four times.

She next faces the winner of Spanish seventh seed Paola Badosa and unseeded Swiss Stefanie Vogele.

Clara Burel also advanced with a 7-5 2-6 6-0 win against Aliaksandra Sasnovich in a match where both struggled on serve, combining for 14 breaks and seven double-faults.

Burel, who had the only two aces of the match, will play second-seeded Fiona Ferro in an all-French quarter-final.

Australian Associated Press