Players were handed ice towels to cool down as temperatures soared on the courts at Melbourne Park, reaching 67 at Rod Laver Arena in what has become a right of passage for players in the first grand slam of the year.
Germany’s Andrea Petkovic said that heat and fatigue had sapped her mental game, after she was knocked out by the United States' Lauren Davis following a marathon first match and a doubles.
"I just feel like somebody switched me off at one point and I couldn’t’ think straight. I was just trying to survive," said the World no. 98.
"I feel more for the spectators. There are a lot of elderly people who like to watch the tennis, there are kids, there are people who heave health issues," Petkovic told Reuters.
"A lot of players, they are in survival mode. I think for everybody... it would be really good to close the (roof) covers."
The Australian Open has only twice invoked its extreme heat policy, when temperatures above the 40 degrees Celsius mark in 2009 and 2014 halted matches.
Australia's Bureau of Meteorology expects temperatures to reach 42 in central Melbourne on Friday, but humidity would be too low to invoke the policy, organisers said.
That decision is taken when the ambient temperature exceeds 40 degrees and the wet bulb globe temperature index reading exceeds 32.5 degrees.
In 2014, a ball boy and player fainted during a match, and organisers were criticised for allowing the tournament to continue. Since then, they have planted trees and added 3,200 square metres of shade in the redevelopment of Margaret Court.
Ninth seed Johanna Konta tumbled out of the second round in blazing sunshine and windy conditions, after a defeat by World number 123 Bernarda Pera.
On whether organisers should be quicker to close the roofs, Konta said: "That's quite nice for the people who are under the roof. Not so nice for the people who are not. But that's a tournament decision. I think you deal with whatever comes."
Fans had come prepared in long sleeves and legionnaire hats, bringing bottled water and food to avoid getting stuck in queues exposed to the sun.
Keith Jenkins, 66, a regular Open goer, sat under a canopy wearing a beige floppy hat and green checked shirt.
"On the outside courts you are in the full sun – you’re just baking. But all the players play the summer circuits, so they’re used to it," he said.
"Some people say, put the roof on and then it’s just like indoors. There’s no heat conditions, there’s no wind conditions. But then it doesn’t become a battle of attrition."
(Reporting by Melanie Burton; Editing by Amlan Chakraborty)
