RIO DE JANEIRO, Brazil – Danka Kovinic has enjoyed a meteoric rise up the rankings in the last 12 months, but was made to work in the first round of the Rio Open; the No.3 seed beat American Sachia Vickery, 6-3, 5-7, 6-4 in just over two hours.

“It was so tough to play,” a tired Kovinic admitted after the match. “It’s very humid and hot here, and I came from Serbia, where it’s very cold. For me, it was very hard to play; I felt like I didn’t have energy, but somehow I found a way to finish the match.

“I really don’t feel good right now.”

At a career-high ranking of No.50, the 21-year-old Montenegrin next plays the winner of veterans Romina Oprandi and Sílvia Soler Espinosa for a spot in the quarterfinals and the chance to pocket valuable ranking points that can help her return to Rio later this summer for the 2016 Summer Olympics.

“I’ll try to do the best to earn as much points as I can; I really need them for the Olympic games. That’s my goal for this year.”

Earlier in the day, No.5 seed Polona Hercog took out qualifier Jennifer Brady, 6-4, 6-2, and resurgent American Shelby Rogers upset No.8 seed Andreea Mitu, 6-2, 6-2. Mitu’s countrywoman Ana Bogdan defeated local wildcard Gabriela Ce, 6-2, 6-3, while Paraguay’s Veronica Cepede Royg recovered from a set down to defeat Anna Tatishvili, 6-7(4), 6-1, 6-3.

An intriguing first round match concerns a pair of wildcards in Brazil’s Beatriz Haddad Maia and former World No.21 Sorana Cirstea, who is playing her first WTA event since last fall in Tokyo; despite a rain delay in the second set, Cirstea emerged victorious, 6-2, 6-1.