"Yeah it was a tough set first. The match was going to be tricky ... the weather was not helping," Azarenka said. "I had to play a little bit and find my rhythm."
Both players had trouble holding serve, with a combined six service breaks in 66 minutes leading into the tiebreaker. No. 91-ranked Larsson was taking big cuts with her ground strokes and forcing Azarenka to defend. But the two-time defending champion started getting on top in the second set and didn't drop serve again.
Both players draped bags of ice over their necks and shoulders and sat under covered seats in the changeovers. They retreated into the shade at the back of the courts between points.
Temperatures hit 104 degrees early on the second afternoon of the tournament and were expected to rise. A hot, gusty breeze swirled across the venue. Spectators covered their heads and shoulders with damp towels to cool off.
On the men's side, three-time defending champion Novak Djokovic improved his winning streak at Melbourne Park to 22 matches with a routine win over Lukas Lacko of Slovakia.
No. 13 John Isner, the only seeded American man in the draw, retired after losing the first two sets 6-2, 7-6 (6) against Martin Klizan. He called for the trainer after the tiebreaker, tapped his racket on the ground three times while deliberating whether to go back out, and only played on for a few minutes in the third set. Tournament officials said he retired with a foot injury Isner won the title last weekend at Auckland, where he was playing with an injured right ankle.
It was the second retirement in as many matches on Court 6. No. 25 Alize Cornet only had to win one game before Polona Hercog of Slovenia retired with an undisclosed injury.
Wozniacki had a 6-0, 6-2 win over Lourdes Dominguez Lino.