Rafael Nadal put on an awesome performance to reach the Australian Open last 16 on Saturday and Roger Federer and Andy Murray also hit top gear as the title race began to narrow.
With Victoria Azarenka a class apart in her third-round win, Nadal stormed past France's Gael Monfils 6-1, 6-2, 6-3 to underline his challenge to Novak Djokovic's three-year Melbourne reign.
Federer was typically fluent in his 6-2, 6-2, 6-3 win against Teymuraz Gabashvili and Murray, continuing his strong recovery from back surgery, was a convincing winner over Feliciano Lopez.
With sharply cooling temperatures bringing an abrupt end to four days of 40 Celsius (104 Fahrenheit), there was a businesslike feel as the men's and women's contenders set about reaching week two.
Federer said his Grand Slam struggles last year, when he fell early at Wimbledon and the US Open, were past him as he dismantled Russia's Gabashvili, the world number 79.
"It was a tough year last year and it took some time to figure out what I needed to do to feel better and to get my confidence back, because that's what I thought it was mostly," said Federer, seeded six.
"For the last four to five months I feel that I'm back to normal again and at least I feel I've done the work to catch up and haven't had any setbacks, so it's very positive."
Murray gave a brief scare when he clutched his back in the first set but he moved unhindered thereafter to win 7-6 (7/2), 6-4, 6-2 and move into the round of 16 without dropping a set.
"Today was a big step up for me. Feliciano is a top-30 player. He's a tricky opponent to play," Murray said.
In the evening session, Nadal was superior in all departments to the entertaining but inconsistent Monfils, winning in just over two hours.
Nadal will next face Japanese number one Kei Nishikori, who reeled off the last 10 games against Donald Young to end American interest in the men's competition.
Bulgaria's Grigor Dimitrov weathered Milos Raonic's powerful serve to reach his first Grand Slam last 16, where he will face Roberto Bautista Agut, the Spanish surprise package who ousted Benoit Paire.
France's Stephane Robert became the first "lucky loser" to reach the Australian Open fourth round when he beat Slovakia's Martin Klizan. His prize is a match with Wimbledon champion Murray.
And in an all-French clash, 2008 finalist Jo-Wilfried Tsonga ended the injury-defying run of Gilles Simon, who hobbled out of last week's Kooyong Classic, to go into a clash with Federer.
Meanwhile in the women's draw, Azarenka destroyed hapless Austrian Yvonne Meusburger for the loss of just one game, winning 6-1, 6-0 to set up a rematch of last year's semi-final with Sloane Stephens.
Stephens beat Elina Svitolina to progress and she said last year's controversy, when Azarenka was accused of using a medical timeout to calm her nerves at a critical moment, would have no bearing.
"That has nothing to do with this year. I don't even remember half the stuff that happened. It's okay," said the 20-year-old American.
Former champion Maria Sharapova, returning from a shoulder injury, faced down a challenge for a second successive match before beating France's Alize Cornet 6-1, 7-6 (8/6).
Sharapova will next play Slovakian seed Dominika Cibulkova, who beat Spain's Carla Suarez Navarro. Serbia's Jelena Jankovic won against Kurumi Nara to set up a meeting with Romanian Simona Halep.
But former world number one Caroline Wozniacki took a tumble when she was shocked by the unheralded Garbine Muzuruga, 20, who extended her best ever Grand Slam run.
Next up for the emerging Spanish star is Polish fifth seed Agnieszka Radwanska, who came from a set down to oust Russia's Anastasia Pavlyuchenkova.
Defending champion Novak Djokovic charged into the Australian Open fourth round and Serena Williams smashed the 39-year-old record for wins at the tournament as a sweltering heatwave finally eased.
Djokovic, gunning for a fourth straight victory at the season's first Grand Slam, simply had too much firepower against Uzbekistan's Denis Istomin as he racked up his 24th consecutive win in Melbourne.
The world number two is also unbeaten since last year's US Open, making him narrow favourite over hot rival and 13-time Grand Slam champion Rafael Nadal, whom he cannot meet until the final.
Djokovic, 26, eased through the first two sets and, after being broken for the first time when serving for the match, he broke straight back and wound it up 6-3, 6-3, 7-5.
"Things got tense towards the end of the match. I made some double-faults. This is what happens," he said. "I could have easily got into a tiebreak and then it's very even, very unpredictable who is going to win the third.
"I didn't want to drop the third set, obviously, so I was very focused to get the job done in straight sets."
Djokovic, playing in the evening, benefited in a sharp drop in temperatures which have topped 40 Celsius (104 Fahrenheit) for four days straight, one of Melbourne's most severe heatwaves.
Earlier, Williams opened the day's events on a baking hot Rod Laver Arena but she appeared untroubled as she beat Daniela Hantuchova 6-3, 6-3 to reach the fourth round for the loss of 12 games.
Shielded from the sun by a pink cap, the 32-year-old world number one wielded a killer serve as she overpowered the Slovak in 80 minutes, setting up a meeting with Serbia's Ana Ivanovic.
It was Williams' 61st victory at the tournament, breaking the record set by 11-time champion Margaret Court up to 1975. Williams' first Australian Open match win was on her debut aged 16 in 1998.
Asked which had been her favourite victories, she deadpanned: "All the finals I was able to win."
China's Li Na soon joined Williams in the next round but she took a very different route after flirting with disaster in a three-set struggle with Lucie Safarova.
Safarova narrowly missed a forehand on match point in the second set and Li then played a nerveless tiebreak before taking it 1-6, 7-6 (7/2), 6-3 in two-and-a-half hours.
"I think the five centimetres (two inches) saved my tournament," said Li, referring to Safarova's miss on match point. "If she hit it in, I think my whole team are on the way to the airport.
Li will now play Russia's 22nd seed Ekaterina Makarova, who beat Romania's Monica Niculescu, while Italian Flavia Pennetta beat Mona Barthel to set up a clash with Germany's Angelique Kerber.
In the evening session, Australia's Sam Stosur suffered further heartbreak at her home Grand Slam when she threw away a one-set lead against Ivanovic.
Stosur, who held her nerve when a first-set tiebreak was interrupted by rain — while she was on set point — then faded as Ivanovic won 6-7 (8/10), 6-4, 6-2 to set up a meeting with Williams.
In 12 visits to the Australian Open, 2011 US Open champion Stosur has never managed to get past the fourth round.
In the men's draw, Spain's super-fit Ferrer again proved impregnable as he ground down France's Jeremy Chardy 6-2, 7-6 (7/5), 6-2 to reach his 15th consecutive Grand Slam fourth round.
Seventh seed Berdych ended the fairytale run of Damir Dzumhur, the first man from Bosnia and Herzegovina to compete at a Grand Slam whose brave performances won fans at home and abroad.
Berdych will next play South Africa's Kevin Anderson, who came through a five-set scrap with Edouard Roger-Vasselin of France. Italian seed Fabio Fognini beat American Sam Querrey in straight sets to set up a last-16 clash with Djokovic.
Despite day-time temperatures of 42 Celsius, organisers opted not to repeat Thursday's use of emergency rules which allow them to suspend play on outside courts and close the retractable roofs on the two main stadiums.
China's Zheng Jie was the latest casualty when she needed medical treatment and a rub-down with ice during her loss to Australia's Casey Dellacqua. However, temperatures dropped nearly 20 Celsius by the evening and they were forecast to stay low over the weekend.
Title favourites Novak Djokovic and Serena Williams shrugged off a second day of intense heat to reach the Australian Open third round Wednesday alongside China's Li Na.
Djokovic, watched by new coach Boris Becker, flew past against Argentina's Leonardo Mayer 6-0, 6-4, 6-4, extending his Melbourne streak to 23 straight wins.
With temperatures close to 40 Celsius (104 Fahrenheit) Williams also took the fast route with a 63-minute demolition of Serbia's Vesna Dolonc.
"It was tough conditions out there. I think it keeps getting hotter. Every day is really hot," said the 17-time Grand Slam title-winner.
Li, twice a finalist at Melbourne Park, subdued a challenge from Swiss teenager Belinda Bencic, touted as the new Martina Hingis, to make the third round for the fifth year in a row.
Spanish third seed David Ferrer beat France's Adrian Mannarino to progress alongside Tomas Berdych, the world number seven, who downed Kenny De Schepper.
Ice packs and energy drinks remained in high demand after Canada's Frank Dancevic fainted and China's Peng Shuai vomited in extreme temperatures on Tuesday.
After a tournament-record nine withdrawals in the first round, Croatia's Ivan Dodig became the latest casualty when he pulled out with cramp in the fourth set of his match against Damir Dzumhur.
Reports said that Dodig thought he might have "died" in the hot conditions, blasting them as unacceptable.
Despite complaints about the heat, which is forecast to remain for another two days, organisers have baulked at halting play, saying humidity is low enough to mitigate any risk.
Djokovic, a previous casualty of the Australian heat after retiring during his 2009 quarter-final, said his switch to a gluten-free diet had helped him cope. "I've matured and I got physically better and changed a few things in my diet that helps me to maintain the fitness at a high level throughout the whole year," he said.
"Obviously it wasn't always like this. Even today it was as hard for him (Mayer) as it was for me and you have to find that mental edge in the tough moments and overcome the conditions."
The three-time defending champion had been off his clinical best in his first-round match, but he returned to his familiar precision against Mayer, hitting 30 winners to just 11 unforced errors.
Williams also lived up to her destructive reputation against Dolonc as she goes in search of her 18th Grand Slam title, a tally which would match Chris Evert and Martina Navratilova.
"I'm still excited to just be here and be playing in front of this crowd. I'm happy to still be alive (in the tournament)," she said.
Li raced through her first set against the 16-year-old Bencic, but was forced to fight for the second before taking the match 6-0, 7-6 (7/5).
The former French Open champion admitted she was not at her best but said she was glad to make it through and escape the steamy conditions in straight sets. "Every day is different, I cannot say I played 100 percent," Li said. "Of course I cannot play 100 percent every day, but (I played) at least 60, 65 percent."
Ferrer dropped the second set against Mayer but came back to win 7-6 (7/2), 5-7, 6-0, 6-3 in a typically dogged display.
Jeremy Chardy prompted a racquet-smashing fit from Ukraine's Alexandr Dolgopolov when he edged their ultra-tight four-setter, which included three tie-breaks.
Big-serving Polish 20th seed Jerzy Janowicz ousted Spain's Pablo Andujar in four sets, and French ninth seed Richard Gasquet beat Russian veteran Nikolay Davydenko in three.
Among the evening matches, eighth seed Stanislas Wawrinka battled past Alejandro Falla in four sets, and Serbia's Ana Ivanovic thrashed Annika Beck 6-1, 6-2.