Novak Djokovic made light work of opponent Hugo Dellien in the opening round of the men's singles at Tokyo 2020, beating the Bolivian 6-2 6-2.
However, it was a more grueling afternoon than the scoreline suggested, with the players having to contend with soaring temperatures and stifling humidity.
CNN's weather team said temperatures on Saturday climbed to near 34°C (93°F) across the greater Tokyo region, with "oppressive" humidity levels above 80%.
“Very tough," Djokovic said of the conditions. "Today, from also speaking to the other players, it was the hottest day so far.
"Humidity is brutal, because it’s very hot and also very humid, so the hard courts absorb the heat, and it stays trapped in there. Not much wind, not much breeze.
"Maybe other days there was a bit more wind, which helped refresh and cool down, but not much today, so it was challenging definitely, but I’m pleased to overcome the first hurdle.
“I was solid on the court, can always do better, but first match I’m satisfied.”
Djokovic, who recently claimed his 20th grand slam title with victory at Wimbledon, is aiming to become the first man in history to achieve the 'Golden Slam,' winning all four grand slams and Olympic gold in the same year.
Earlier on Saturday, world No. 2 Daniil Medvedev had suggested the tennis matches be scheduled later in the evening to allow players to compete in cooler conditions.
“I agree with him 100%," Djokovic said. "I actually asked as well. My team captain Viktor Troicki was speaking to the referee a couple of times. To be honest, I don’t understand why they don’t start matches at, say, 3pm.
“I’ve heard for tennis there is some kind of curfew they have to finish at midnight, but if that’s the case, I’ve just finished the last match and it’s not even 5pm, we still have 7 hours to play.
"They have lights on all the courts, they’re going to make life much easier for all of us tennis players, I just don’t understand why they don’t move it.
“It’s actually for the TV broadcasters even better, because the later you play, the better it is for the United States and the time zones in Europe.
"I don’t know, maybe ITF (International Tennis Federation) can give you a better answer to why they chose to be played in the middle of the day. I doubt they will change the decision, but we’re hoping that they will.”