Canada's Frank Dancevic passed out, Peng Shuai of China threw up and players complained the seats were burning them at the changes of ends as temperatures hit 42.2°C (108.2°F) at Melbourne Park.
Amid all the chaos and criticism of tournament organisers for letting play continue, Andy Murray hid nicely in the shadows, saving his energy for the battles ahead.
His 6-1, 6-1, 6-3 victory over Japan's Go Soeda, the world No.112, was better than even he had expected, especially after having played just two competitive matches following back surgery in September.
Having played down expectations, he could do well again here - he has reached the final three times in the past four years - and the fist pump and celebrations after what was on paper a straightforward win told their own story.
Even the sun played ball for Murray as it dipped behind the stands, allowing the Wimbledon champion to cool down ever so slightly and he responded by taking Soeda apart.
You know that you're in for some rough weather when a tournament has an extreme heat policy and organisers implemented the first two phases yesterday, allowing the women to have a 10-minute break after the second set.
The final phase - the closing of the roof over the respective showcourts - was not required, tournament organisers said, because the level of humidity was low.
It was a decision that irked Murray somewhat and positively riled others, including Dancevic, a veteran Canadian now, who folded, literally and metaphorically, against the Frenchman Benoit Paire.
"I think it's inhumane, I don't think it's fair to anybody, to the players, to the fans, to the sport, when you see players pulling out of matches, passing out," he said. "Having players with so many problems and complaining to the tournament that it's too hot to play, until somebody dies, they'll just keep putting matches on in this heat. I don't think it's fair and I know a lot of players don't think it's fair."
Roger Federer, a straight-sets winner over James Duckworth, the Australian wildcard, in his first match since hiring Stefan Edberg to his team, believes the roof should stay open no matter what, to be a truly equal test.
But Maria Sharapova, who beat Bethanie Mattek-Sands 6-4, 6-4 in the late match, said no-one was happy. "I'm sure it was very difficult for everyone," she said. "Everyone, except the meteorologists and the doctors, seemed to have the same opinion about the weather."
Had the roof been closed over Hisense Arena, Murray would have enjoyed far cooler conditions, but the Scot is something of a tennis egalitarian, and would rather the rules protected all the players and not just the stars who always play on the big courts.
"The players that play on the big courts are obviously lucky because they always know they're going to get their matches done and they always know they're going to get to play, and that helps," Murray said. "That's now obviously the case at Wimbledon and here, if you play on the main courts.
"I think that's going to change over time, because they'll get an extra roof at Wimbledon, they're going to get three here; they're doing one at the US Open. It's just, for all of the players. I don't want them just to close the roof so I can get my matches done."
Before the tournament began, Murray talked of the need to get things done quickly in the first week, to conserve his energy for the race to the title. And his cause will not have been hurt by the withdrawal through injury of John Isner, the American No.1 who was forced out by the recurrence of an ankle issue.
Isner, who was trailing Martin Klizan, of Slovakia, by two sets to love, was seeded to face Murray in the last 16 and his departure means the Scot should have a easier route to the quarter-finals.
He will not take anything for granted, though, and nor should he. Although his next opponent, the French qualifier Vincent Millot, has a lowly ranking of No.267, his pedigree is fine: his father Philippe played football for Saint-Etienne in the French league alongside the great Michel Platini. He booked his place in round two with a five-set victory over another qualifier, the American Wayne Odesnik, a result which pleased Murray, who said of Millot: "I'm glad he won".
Murray's animosity towards Odesnik refers to the 2010 case when he admitted importing human growth hormone into Australia and was banned for two years. His ban was reduced to one year on appeal and, since his return to the Tour, Odesnik has cut a lonely figure, hovering outside the top 100.
Millot, though, expects to have his hands full when he meets Murray tomorrow. "In qualification I felt a little pain in my back but now it is getting better," he said. "I hope so. And I hope he is not better."
The hyped up match between the No.1 seed Nadal and Bernard Tomic lasted just one set, which the Spaniard won, as Tomic was forced to quit because of a left thigh injury.
Lleyton Hewitt, who beat Federer to win the Brisbane title, endured another epic Melbourne battle but eventually went down in five sets to Italy's Andreas Seppi.
The performance of the day arguably came from Gilles Simon, the Frenchman, who almost pulled out with a sprained ankle but then outlasted Daniel Brands of Germany 16-14 in the final set.
Victoria Azarenka, the two-time defending women's champion, Agnieszka Radwanska and Caroline Wozniacki all advanced to the second round.