Caroline Wozniacki resorted to dreaming to survive a fierce heatwave at the Sydney International, while Eugenie Bouchard was relieved not to pass out in 41.5C heat at the tennis tournament.
Bouchard and Wozniacki both described the conditions as "brutal" on Wednesday, when they featured in contrasting quarter-finals.
Former Wimbledon finalist Bouchard required 76 minutes to upset world No.27 Anastasia Pavlyuchenkova 6-2 6-3 to reach her first WTA semi-final in almost a year.
Bouchard next faces Sydney-born Brit Johanna Konta, who disposed of rising Russian Daria Kasatkina 6-3 7-5.
Barbora Strycova conquered former world No.1 Wozniacki 7-5 6-7 (7-6) 6-4 in a punishing clash that lasted three hours and 19-minutes, with both players receiving treatment for foot injuries on Ken Rosewall Arena.
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Strycova will take on 2013 winner Agnieszka Radwanska, who easily accounted for Chinese qualifier Duan Yingying 6-3 6-2 on Wednesday night.
Wozniacki was attempting to end a run of seven Sydney International visits without getting past the quarter-finals. Nobody could fault her endeavour in stifling heat.
The Dane battled back from 5-2 down in the second set and 5-0 in the tiebreaker but fell in the third set.
"It was brutal out there, and it was really hot. But you know, you just try and think like you're on a beach drinking pina coladas," Wozniacki said.
"That's basically your train of thought. You know that it's the same for both players, so I was just trying to mentally just try and keep cool. But it was really, really hot out there."
"I thought we played actually some really good tennis as well, considering all these conditions."
Wozniacki broke the world No.19 twice in the decider, but gave up three games of her own and will now look to recuperate ahead of next week's Australian Open.
"On the positive side of things, I can eat whatever I want now because I have burned a lot of calories today. I'll definitely have an ice cream, for sure," Wozniacki said.
Bouchard wasn't on court for nearly as long but still felt the heat.
"It was really hot. It was pretty brutal," the Canadian said.
"All I was thinking about was the next changeover and drinking water and the ice towel, and wishing we had ice baths on the court ... (and trying) not to pass out.
"But luckily the match before us was so long that by the time we were out there, there were some clouds. By the end of the match, it was OK."
Bouchard has enjoyed three consecutive wins over top-30 opponents in Sydney as she aims to break a two-and-a-half-year title drought.
Konta relished the chance to spend more time in Sydney, where her sister lives.
"I'm just really happy I get to stay here a little bit longer," 2016 Australian Open semi-finalist Konta said.
