Australian Brett Rumford overcame stifling conditions to take a share of the lead at the Perth International, but drawcard Victor Dubuisson and two past champions bombed out on Friday.
Rumford is equal top with American Peter Uihlein at 11-under after posting a seven-under 65 in his second round.
World No.21 Louis Oosthuizen is lurking dangerously one shot further back after shooting an impressive eight-under 64 in his second round.
But the news wasn't nearly as good for Dubuisson, who missed the cut by a wide mark after finishing at four-over through his first two rounds.
The temperature reached 36 degrees in Perth on Friday, and Rumford made sure to keep his fluids up - especially after undergoing surgery last year to have 30cm of his small intestine removed.
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"This is the hottest conditions no doubt I've played in (since my surgery)," Rumford said.
"But the body's great. There's no signs whatsoever. That's all history now.
"It's a hilly golf course, so it's going to take a lot out of you. So it's about making sure you maintain your food stocks and keep hydrated."
Oosthuizen was on track to join Rumford and Uihlein at the top of the leaderboard, but a missed short-range putt on the final hole meant he had to settle for outright second.
"I just over read it," Oosthuizen said.
"I hit it a ball outside the hole.
"It was the first real putt I had in the shadows today. I took my glasses off, and I misread it a little bit. It's not going to bother me though."
Dubuisson wasn't the only notable name to crash out, with defending champion Thorbjorn Olesen (five-over) and 2013 title winner Jin Jeong (four-over) also failing to make the cut.
Dubuisson - the world No.37 - has now missed two consecutive cuts since making a recent switch in equipment.
But instead of getting down on his latest flop, the 25-year-old was more than happy to hold Sunshine the Koala for a photo shoot after his second round.
Dubuisson was so smitten by the furry marsupial that he gave it a quick peck on the lips.
But it's the last piece of action he'll get at Lake Karrinyup this year after his disappointing display on the golf course.
Australian Marcus Fraser, who won the Maybank Championship in Malaysia last week, is at two-under alongside Peter Senior.
Uihlein was grouped with Dubuisson for the opening two days, but he said the Frenchman kept his emotions in check.
"You can never tell with Victor. He's like the Mona Lisa, you never really know what's going on," Uihlein said with a laugh.
"He's a great player. He could win Doral next week by 10, he's that good."
