And after her 6-1, 6-2 win over Vesna Dolonc on Wednesday, the second consecutive scorching day at the season's first major, Williams said she could remember hotter matches.
By extending her winning stretch to 24 matches dating back to August, and improving her career mark to 60-8 at Melbourne Park, she also equaled Margaret Court's record 60 match wins at the Australian Open in the Open era.
Court, who won seven of her 11 Australian titles before the Open era began in 1968, has a show court named in her honor adjacent to Rod Laver Arena.
On day three at Melbourne Park, the center court was -- at least according to the two fans holding up a sign -- "Serena's Arena."
The heat topped 40 Celsius (104F) during the 63-minute match, and peaked at just under 42 C (108 F) later during Novak Djokovic's 6-0, 6-4, 6-4 win over Leonardo Mayer. Second-seeded Djokovic, aiming to be the first man in the Open era to win four consecutive Australian Open titles, didn't face a break point.
Williams fended off the only break point she faced with an ace, one of her 10 in the match. She hit 24 winners, sticking to the ideal strategy of keeping the points short on a hot day.
She said didn't even go outside Tuesday because conditions "were a little bit extreme," adding that the prospect of the scorching temperatures had even interrupted her sleep.
"I kept waking up in the middle of the night last night just paranoid. I just wanted to stay hydrated," she said. "The last thing I want to do is to cramp in this weather. It can happen so easy."
Williams next meets No. 31-seeded Daniela Hantuchova, who was on court for 3 hours, 13 minutes in her 6-3, 3-6, 12-10 win over Karolina Pliskova.
Temperatures topped 42 Celsius (108F) on Tuesday, and there were a total of nine retirements in the first round, equaling a Grand Slam record. It wasn't quite as stifling Wednesday, due to some cloud cover and less of the hot wind. The forecast is for the heat wave to continue until Friday.
Li Na opened proceedings Wednesday when she completed back-to-back wins over the two youngest players in the draw.
The 2011 French Open champion, a two-time finalist at Melbourne Park, conceded just 10 points in the first set en route to a 6-0, 7-6 (5) win over 16-year-old Belinda Bencic. Li will play No. 26 Lucie Safarova in the third round.
No. 9 Angelique Kerber advanced to a match against American Alison Riske, who trounced Yanina Wickmayer 6-1, 6-1. Australian wild-card entry Casey Dellacqua upset No. 18 Kirsten Flipkens 6-3, 6-0.
The tournament's heat rule went into effect in the first match on Margaret Court Arena, giving No. 15-seeded Sabine Lisicki and Monica Niculescu a 10-minute break after the second set.
Niculescu returned to win 2-6, 6-2, 6-2 and will next play No. 22 Ekaterina Makarova, who followed up her first-round win over Venus Williams with a 6-2, 7-5 victory over American Irina Falconi.
No. 28 Flavia Pennetta beat Monica Puig in straight sets to set up a third-round match against Mona Barthel, a 4-6, 6-3, 6-4 winner over Thailand's Luksika Kumkhum.
On the men's side, Djokovic extended his winning streak to 26 matches but had a brief scare while serving at 3-0 in the first set when he turned over on his left ankle, tumbling to the court.
It didn't warrant medical attention during the next break in play and he took the opening set in just 22 minutes, allowing Mayer to win just eight points.
"It was just I slipped a little bit," Djokovic said. "It was an instant discomfort, but it was OK after."
No. 3 David Ferrer beat Adrian Mannarino of France 7-6 (2), 5-7, 6-0, 6-3 to progress along with No. 7 Tomas Berdych and No. 9 Richard Gasquet, No. 17 Tommy Robredo, No. 20 Jerzy Janowicz and No. 29 Jeremy Chardy.
Florian Mayer beat No. 14 Mikhail Youzhny, Uzbekistan's Denis Istomin beat No. 30 Dmitry Tursunov and Bosnian qualifier Damir Dzumhur advanced when No. 32-seeded Ivan Dodig retired with cramps while leading in the fourth set.
Sam Querrey fired 19 aces, saying he had "one of the best service days of my life" in a 6-2, 6-3, 6-4 upset win over No. 23 Ernests Gulbis.
