The Australian Open's chief medical officer admitted playing conditions this week may not have been humane after Jamie Murray became the latest victim of Melbourne's searing heat.
The Scot suffered heatstroke in the 40C-plus temperatures and needed extensive treatment after he and Australian partner John Peers won their first-round doubles match at Melbourne Park.
It was not clear whether the elder Murray brother would be able to carry on in the tournament even with a day of rest.
After beating Vincent Millot in his second-round singles match, Andy Murray said of his sibling: "I think he's doing better. He went back to the hotel earlier. I spent an hour or so with him when I got here, and then checked up with him a couple of times.
"But he wasn't in a great way. He was struggling for a good three or four hours after the match.
"It's never happened to him before. When the cramps happen - I don't know how dangerous they are, but they're very, very uncomfortable.
"When one part of your body goes and then you move, the opposite muscle goes. When it happens the first time, it's pretty scary.
"We just tried to make sure someone was with him throughout the day. He drunk loads when he got off the court. He was finding it quite hard to eat. Hopefully he'll be fine tomorrow."
Jamie was far from the only player to fall foul of the conditions, and there has been a fierce debate raging about whether play should have continued.
The tournament's extreme heat policy was finally implemented just before 2pm on Thursday, not long after Jamie had left court, with the temperature measured at 42C.
Whether to put the policy into effect is this year entirely at the discretion of tournament referee Wayne McKewen after a change in the rules.
McKewen uses the Wet Bulb Globe Temperature reading, which takes into account humidity and wind direction as well as heat.
He had been criticised for allowing play to continue throughout Tuesday and Wednesday despite temperatures soaring above 40C.
Canadian Frank Dancevic and a ball boy both fainted on court, three players withdrew mid-match because of the effects of the heat and spectators left in their droves.
Speaking to BBC Radio Five Live, chief medical officer Tim Wood defended the decision-making, saying: "We evolved on the high plains of Africa chasing antelope for eight hours under these conditions.
"There will be some players who complain, and no-one is saying it is terribly comfortable to play out there, but, from a medical perspective, we know that man is well adapted to exercising in the heat. Whether it is humane or not is a whole other issue."
Play was delayed on uncovered courts for just over four hours because of the heat, with the roof shut on Rod Laver and Hisense Arenas.
Like Jamie, American Varvara Lepchenko found the conditions tough going in her 4-6 6-0 6-1 defeat by Simona Halep.
Lepchenko took a medical time-out in the second set and was rubbed down with ice while she lay across two chairs.
The 27-year-old described her ordeal after the match, saying: "I started feeling dizzier and dizzier. In the second set I couldn't focus on my returns, I couldn't see the ball, and then it was just like one step leading to another.
"Towards the middle of the second set I started feeling more and more dizzy, the time was going so fast and I needed more time between the points. I started feeling really hot on the top of my head and at one point I completely lost it."
The 27-year-old was unhappy she had been made to play in such conditions, adding: "I think they definitely should have not started the matches in the first place.
"And the same goes for a couple of days ago when I played my (first-round) match. It was the hottest time of the day and I got caught up in that.
"Somehow I survived, but today it didn't work. This is just too much."