Rain, extreme heat force Open suspensions

Days two and three of the Australian Open schedule have been thrown into chaos by Melbourne's weather, with night-time downpours compounding three hours' worth of earlier delays due to extreme heat.

The extreme heat policy was enacted for the best part of three hours on a scorching day two of the Australian Open on Tuesday, with action suspended on the outside courts at Melbourne Park as the temperature peaked at 37C.

Action continued throughout the break with the roof closed on Rod Laver Arena, John Cain Arena and Margaret Court Arena, while play eventually resumed on all courts shortly after 1700 (AEDT).

But play later had to be suspended for a second time on the outside courts at around 2000 after a sudden downpour hit Melbourne Park, with none of those matches allowed to resume until 2100 - and either postponed again or never resuming.

As of Tuesday night, 10 matches had been cancelled and another 12 postponed at varying stages.

They will all need to be recommenced or started on Wednesday, when the other side of the draw will start the second round.

Thanasi Kokkinakis was only five points away from an easy straight-sets win over Fabio Fognini, leading 6-1 6-2 4-2 with the Italian serving at 15-40.

Before competition was halted early in the afternoon, players on the outside courts had resorted to applying ice packs and taking shelter under umbrellas in an attempt to avoid the worst of the conditions.

Kaia Kanepi, the 37-year-old No.31 seed from Estonia, was among those who visibly struggled in the conditions during a tough three-set loss to Australian Kimberly Birrell.

"I'm from the sunny Gold Coast (and) I'm used to the conditions and maybe she wouldn't have been," said Birrell.

"I really like these conditions.

"I like feeling like I'm working hard and sweating and getting into the fight.

"I think that's when I play some of my best tennis."

Playing on RLA before the roof was closed, Belarusian fifth seed Aryna Sabalenka was relieved to have needed only 69 minutes to dispatch Czech Tereza Martincova 6-1 6-4 to reach the second round.

"I definitely need to cool down," Sabalenka said.