By Nick Mulvenney
MELBOURNE (Reuters) - World number one Serena Williams made light of scorching temperatures on the fourth and final day of the Melbourne Park heatwave to blast her way into the last 16 of the Australian Open for the loss of just a dozen games on Friday.
Li Na's progress was less imperious and the Chinese fourth seed escaped defeat by a matter of centimeters in her third round match, while Spain's David Ferrer continued to carve his way through the men's draw largely unnoticed.
Novak Djokovic later attempts to clear the third hurdle in his path to a fourth straight Australian Open title when he takes on Denis Istomin in the final match on Rod Laver Arena.
A fourth day of temperatures in excess of 42 degrees Celsius (110 degrees Fahrenheit) meant the demand for ice, liquid and sunscreen remained high at Melbourne Park but there was no repeat of Thursday's suspension of play.
Li's compatriot Zheng Jie seemed to suffer most obviously during her 6-2 6-4 loss to local Casey Dellacqua on Rod Laver Arena before a cooling breeze eased conditions.
"I was a little bit sick and also my mind was not working, I felt," said the former Melbourne Park semi-finalist, who admitted she might need to train in hotter conditions before next year's tournament.
"I just watched the ball and just hit it. I didn't know where I hit it."
Temperatures are forecast to drop considerably on Saturday, a huge relief to players and organizers alike after four days of rows over what constitutes dangerous conditions.
"I definitely look forward to playing in the cooler temperatures," said Williams, whose 6-3 6-3 win over Daniela Hantuchova was a record 61st at the Australian Open, taking her past local great Margaret Court's 60.
That Williams achieved her victory in 80 minutes without firing on all cylinders - "I wasn't fully on today" - was another warning to her rivals that her sensational form in 2013 was by no means a final flourish at the end of her career.
"For whatever reason, I feel like I just never was really able to reach my full potential, and I feel like recently I just have been able to do a little better," said the 32-year-old, who is in the hunt for her sixth Australian Open title.
With just the one grand slam title to the American's 17, Li attracts considerably lower expectations but was still expected to deal easily enough with Lucie Safarova on Hisense Arena.
The Czech, however, raced through the first set 6-1 and then forced a match point in the second, which she failed to convert by the smallest of margins when her backhand down the line was called out, a decision confirmed by Hawk-Eye.
"I think the five centimeters saved my tournament," said Li, who rallied to win the subsequent tiebreak and then seal 1-6 7-6 (7-2) 6-3 victory. "If she had hit it in... the whole team would be on the way to the airport."
Ninth seed Angelique Kerber, Li's potential quarter-final opponent, had no such problems in her routine 6-3 6-4 triumph over Alison Riske.
Super-fit Ferrer's attritional style was made for hot conditions and he survived a second set wobble to wear down Frenchman Jeremy Chardy to reach the fourth round at a 15th consecutive grand slam with a 6-2 7-6 (7-5) 6-2 victory.
Ranked and seeded third after Andy Murray missed the back end of last season, Ferrer next faces Florian Mayer with Tomas Berdych or Kevin Anderson waiting in the quarter-finals.
Anderson came from two sets down for the second time in four days to reach the last 16, outlasting Edouard Roger-Vasselin 3-6 4-6 6-3 7-6 (7-5) 7-5 in just under four hours.
The tall South African also trailed 0-4 in the fourth set and 3-5 in the fifth and let out a huge roar when the Frenchman went long to hand him the victory on Margaret Court Arena.
"It was a lot of emotions at the end," said Anderson. "Just a lot of excitement. A little bit of disbelief as well."
Berdych, by contrast, eased into the fourth round without having dropped a set all week courtesy of a 6-4 6-2 6-2 victory over Bosnian qualifier Damir Dzumhur on Hisense Arena.
Even without the accordion that serenaded his victory over Ivan Dodig on Wednesday, Dzumhur once again attracted lively support from his compatriots but Berdych smashed 13 aces and 32 winners to silence them.
With Rafa Nadal, Roger Federer and Murray in the other half of the draw, Berdych knows he will rarely have a better chance to reach a first semi-final at Melbourne Park.
"You know, it's always about the draw," said the Czech seventh seed, who has won all nine of his matches against Anderson.
"Really, if I'm going to have it once pretty good, yes, I take it."
Stan Wawrinka had a day off on Friday after Vasek Pospisil withdrew from the tournament with a bad back, allowing the Swiss eighth seed to rest up before his likely fourth round tie against Djokovic.
(Editing by John O'Brien)