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Temperatures climbed to 90 degrees F inside the Olympic tennis facility on Saturday as players began their first-round matches.

The heat and glaring sun proved to be an obstacle for many athletes, with several Olympians sounding off about the conditions following the first round of competition.

“I feel better but I have a massive headache now so that’s why I was trying to try to cool down after the match and rest, relax a little bit,” Anastasia Pavlyuchenkova told reporters after her 6-0, 6-1 win over Sara Errani. The No. 13 seed was forced to take a medical timeout during her match after falling ill due to the heat.

“They expected the heat and it wasn’t 100 percent ready for us,” Pavlyuchenkova said, criticizing the tournament for not providing an adequate amount of ice in preparation for the temperatures.

Despite the humidity, Iga Swiatek cruised to a 6-2, 6-2 victory over Mona Barthel to advance to the second round.

“I’m pretty happy that I’m into the second round and not only the humidity and temperature was hard but also the sun because on one side it was pretty hard to serve,” Swiatek said after her match.

Reigning French Open champion Barbora Krejcikova will also move on to the second round in Tokyo after Zarina Diyas retired from their match with Krejcikova leading 5-2.

First-round play continues with Naomi Osaka, whose opening match was pushed back from Saturday to Sunday to account for her Opening Ceremony duties.