Watch: Who are this year's Olympics mascots?
With the Tokyo Olympics being overshadowed by the pandemic and COVID restrictions in the build-up to the Games, now the Japanese summer has taken hold on the opening weekend.
The heat and humidity in Tokyo was becoming a major factor on day one of action across the outdoor events taking place in the capital.
To quell the risk at the tennis, air conditioning units were wheeled out to keep players cool as players dealt with sweltering temperatures on court.
Number two seed Daniil Medvedev, of the Russian Olympic Committee, admitted that the heat was “some of the worst” he had ever experienced following his win over Alexander Bublik.
“I’m not going to lie. But you have to play,” Medvedev said. “That’s the Olympics, you go for the medal. You are not here to cry about the heat.”
But Medvedev added that Games' organisers should move all matches to the evening to avoid the punishing heat.
Meanwhile, Germany's Mona Barthel recorded 10 double faults in her opening defeat after sunlight hampered her ball toss.
Elsewhere, organisers were forced to hose down the sand at the beach volleyball arena at Shiokaze Park after athletes complained that the surface was burning their feet. At the road race competition, cyclists shoved ice packs down their lycra outfits.
Games officials have now rescheduled rugby matches and mountain biking competitions to avoid the burning afternoon sun.
The hockey competition had already scheduled matches either side of the afternoon temperatures, with ice jackets and vests being made available for umpires and technical officials.
However, the rising temperatures were clearly evident on the opening day when Argentina's Lucas Rossi was seen tapping his stick into the head of Spain's David Biosca, who was suffering cramp.
Biosca was on the floor and being aided by an Argentinian player when Rossi took exception to the Spaniard going down with cramp.
On Friday, Russian archer Svetlana Gomboeva had collapsed in the searing heat during the qualifying rounds.
“It turns out that she couldn’t stand a whole day out in the heat,” her coach Stanislav Popov told reporters.
Temperatures have touched 35C in recent days, while forecasters have warned of a potential typhoon hitting Tokyo from Sunday.
The change in weather has been greeted by the surfers. "There's going to be good waves, there's a strong typhoon here off the coast of Japan and we know that the waves are getting bigger," said International Surfing Association president Fernando Aguerre.
Watch: What inspired windsurfer Emma Wilson to become an Olympic athlete?