Australian Open organisers suspended play on Thursday in Melbourne after temperatures rose above 40 degrees for a third successive day.
Play on the outside courts was halted until 6pm local time while the roof on the Rod Laver Arena and Hisense Arena was closed to allow matches to continue as the extreme heat policy was enforced.
"Temperatures in Melbourne have soared above 40 degrees Celsius on Thursday, bringing the rule into effect," a tournament statement read.
"The roof at Rod Laver Arena and Hisense Arena will be closed at the end of the set so play can resume on those courts. Once closed it remains shut until the end of the match.
"For outside courts, play will be suspended at the end of the set until further notice. No matches will be called to outside courts while the Extreme Heat Policy is in place."
Jamie Murray and Australia partner John Peers progressed to the second round in the doubles competition however the Briton is a doubt for the remainder of the tournament as he continues to be treated for heatstroke.
Maria Sharapova and Karin Knapp's three hour and 28 minute third round match was played through the hottest part of the day in Melbourne, with the No.3 seed eventually prevailing 10-8 in the third set.
"There is no way of getting around the fact that the conditions were extremely difficult, and have been for the last few days," said the Russian.
"It's a tough call. The question I have is no-one really knows what the limit is - not the players or the trainers when you ask them if the roof will be closed.
"No-one actually knows what that number is in comparison to humidity or the actual heat. I asked the trainer the other day what it takes for the roof to be closed or matches to be stopped, and she said 'we have no control over this'."
The stoppage comes after complaints from a number of players over play not being postponed earlier in the week. British No.1 Andy Murray said: "I don't know why there's the different rules for the heat, I don't know exactly why that is. If there's a medical reason for it, then I'm fine with it, if there isn't, I'm not fine with it. That's it."
A series of players required medical time outs to treat heat exhaustion including American Vavara Lepchenko, who received treatment with ice after losing five successive games before eventually losing to Simona Halep.
"I think they definitely should not have started the matches in the first place," said Lepchenko.
"And the same goes for a couple of days ago when I played my [first-round] match. It was just the hottest time of the day and I got caught up in that.
"Somehow I survived, but today it just didn't work, and I think they should have started matches after the temperature cooled down a little bit, because this is just too much."
The delay is not expected to dramatically affect the schedule going forward however Murray's second round match against Vincent Millot will now begin at 10:30am.