Top-seeded Jelena Ostapenko, 5th-seeded Kristina Mladenovic lose in 1st round of Sydney International

SYDNEY -- French Open champion Jelena Ostapenko was upset 7-6 (3), 6-1 by Ekaterina Makarova on a sweltering opening day of the Sydney International.

No. 3 Ostapenko was one of two highly seeded players to exit the women's draw in the first round, with fifth-seeded Kristina Mladenovic retiring earlier Sunday from her match while trailing Australian wild-card entry Ellen Perez 6-4, 4-2.

Julia Goerges also withdrew from the tournament Sunday after winning the ASB Classic final against Caroline Wozniacki in Auckland, New Zealand.

The conditions forced organizers to activate heat policies -- including longer breaks between sets -- during part of the day, with some areas of western Sydney experiencing the hottest day in almost 80 years with temperatures peaking above 47 Celsius (117 Fahrenheit).

In men's first-round matches, Alexandr Dolgopolov edged Viktor Troicki 6-3, 6-7 (6), 7-5, Damir Dzumhur beat Jan-Lennard Struff 6-1, 6-4 and Paolo Lorenzi had a 7-6 (5), 6-4 win over Jordan Thompson.