Simona Halep saved three match-points before edging past an inspired Lauren Davis 4-6, 6-4, 15-13 in a thrilling marathon to reach the fourth round, while Tomas Berdych overpowered Juan Martin del Potro 6-3, 6-3, 6-2.
Images from Saturday's matches at the Australian Open on Saturday:
Federer eases past Gasquet
Roger Federer eased into the second week of the Australian Open with a 6-2, 7-5, 6-4 win over Richard Gasquet on Saturday evening that kept the Swiss on course for a 20th Grand Slam title.
The 36-year-old defending champion reached the fourth round of the Melbourne Park tournament for the 16th time by shifting up the gears when required to see off his French opponent in just under two hours on Rod Laver Arena.
Gasquet played a solid match, studded with his trademark occasional moments of shot-making brilliance, but that was never enough to overcome one of the best players of all time.
Watched from the stands by 11-times Grand Slam champion Laver, second seed Federer sealed the victory with a backhand winner to set up a first career meeting with Hungarian Marton Fucsovics for a place in the quarter-finals.
Djokovic rolls by Ramos-Vinolas to reach fourth round
Former champion Novak Djokovic added an apparent muscle strain in his lower back to concerns about his problem elbow but still overpowered Spaniard Albert Ramos-Vinolas 6-2, 6-3, 6-3 to reach the fourth round of the Australian Open on Saturday.
After holding serve to lead 2-1 in the second set, the 14th seed took a medical time-out and lay down on Margaret Court Arena as a trainer worked feverishly on his lower back.
The injury did little to restrict the six-times champion Serb as he returned to break the 21st seed in the next game before rolling on to a fuss-free victory in two hours and 21 minutes.
Djokovic will face South Korea's young gun Chung Hyeon in an intriguing intergenerational battle for a place in the quarter-finals.
Relentless South Korean Hyeon Chung ground fourth seed Alexander Zverev into submission in a ferocious battle of young guns to reach the fourth round of the Australian Open on Saturday.
German wunderkind Zverev, tipped as a title contender, led by two sets to one but 58th-ranked Chung was unflappable and roared back to win 5-7, 7-6(3), 2-6, 6-3, 6-0.
It all proved too much for 20-year-old Zverev, who began to unravel in the fourth set, complaining bitterly to the umpire that the lights should be switched on despite it being only 6 p.m. in overcast Melbourne.
"I can't see anything," the German told the official.
The lights were duly switched on but once the bespectacled Chung took the fourth set, there only looked to be one winner.
Zverev, who is yet advance past the last 16 at a Grand Slam, double-faulted twice to gift Chung a break at the start of the fifth and when he dropped serve again two games later he demolished his racket, earning a warning.
The end came quickly as Zverev capitulated, netting a backhand to hand Chung victory as he became only the third South Korean to reach the fourth round of a Grand Slam.
"It was a really tough match, I was just trying to play 100 percent out there," Chung, a year older than Zverev, said on court.
He will play either six-times champion Novak Djokovic or Albert Ramos-Vinolas in the next round.
Berdych overpowers Del Potro
Not many players overpower Juan Martin del Potro but Tomas Berdych did just that to win 6-3, 6-3, 6-2 and reach the fourth round of the Australian Open for the 10th time.
Del Potro arrived in Melbourne with high hopes having re-entered the world's top 10 for the first time since 2014 but was no match for the 19th-seeded Czech.
"Maybe it's the good air here," Berdych said on Hisense Arena to explain his consistency in the year's first Glam.
Berdych struck 52 winners on his way to setting up a clash with Italian Fabio Fognini.
"I think he was just better than me today," del Potro, who had led 5-3 in their previous meetings, told reporters.
"He hit very hard, he served very well and played a smart game. He deserved to win. No excuses today."
Halep wins marathon to reach fourth round
World number one Simona Halep saved three match-points before edging past an inspired Lauren Davis 4-6, 6-4, 15-13 in a thrilling marathon to reach the fourth round of the Australian Open on Saturday.
The Romanian fought back from the brink at 11-10 in the epic final set before serving out the match on the fourth attempt after a taxing three hours and 44 minutes on the centre court at Rod Laver Arena.
A former quarter-finalist at Melbourne Park, Halep closed out the attritional contest on the first match point, when 76th-ranked American Davis, who had gone for broke all match, fired into the tramlines, her 73rd unforced error.
The 26-year-old Halep will meet Japan's Naomi Osaka for a place in the quarter-finals, having carried her injured ankle through a deciding set of 142 minutes.
"I'm almost dead but it was nice that we could show good tennis," Halep said in the on-court interview, raising a laugh from the crowd.
"Definitely it was a very tough match, so long, and I never played the third set so long.
"I just feel that my muscles are gone. My ankle is -- I don't know how it is because I don't feel it any more."
Davis, a baby-faced 24-year-old with a monster forehand, was majestic in defeat, breaking Halep three times when the Romanian served for the match and battling on after losing a toenail late in the game.
She came within an inch of the biggest win of her career when she swooped forward to pounce on a speculative drop-shot and whipped a passing shot to earn three match points at 11-10.
Halep nervelessly saved them all, winning five points in a row for a galvanising hold before Davis removed her sneaker and walked gingerly to her chair.
She took a medical timeout to stall Halep's momentum and the Romanian fumed on the baseline as a trainer worked on Davis's toe.
With Davis hobbled slightly, Halep moved in for the kill but the American saved five break points to frustrate her opponent, and later thanked the net cord for helping her hold again at 12-12.
Halep finally breached Davis's serve at 14-13, and edged a 17-shot rally to come within two points of victory.
Apparently spent, Davis swung hard in a desperate late flurry but missed twice, a forehand sailing just wide to allow Halep to continue her bid for a long-awaited maiden Grand Slam title.
Pliskova serves her way past Safarova
Sixth seed Karolina Pliskova beat fellow-Czech Fed Cup team mate Lucie Safarova 7-6(6), 7-5 to also move into the fourth round.
In a match dominated by serve the 25-year-old fired down 11 aces and offered up only one break point opportunity as she reached the last 16 for the second successive year.
Safarova was equally efficient on her own delivery but finally cracked in the 11th game of the second set to leave her opponent with the opportunity to serve for the match.
She needed no second invitation, crunching three aces including one on match point.
"It's tough to play another Czech player especially as we are Fed Cup team mates," Pliskova said on Margaret Court Arena. "It's always close but I served well and that's the key for me."
Another Czech could be waiting in the fourth round if Barbora Strycova gets the better of lucky loser Bernarda Pera later on Saturday.
Drama-free Keys flies under radar into fourth round
After the commotion that accompanied her run to a first Grand Slam final in New York last year, American Madison Keys has been more than happy to fly beneath the radar in Melbourne.
That was the case again on Saturday as the 20th seed beat 104th-ranked Romanian Ana Bogdan 6-3, 6-4 to progress smoothly through to the fourth round without dropping a set.
"I am always happy if I'm not the drama, and I feel like the US Open I was the drama every night match that I played," the 22-year-old, who was beaten at Flushing Meadows by compatriot Sloane Stephens, told reporters.
"It's a good position for me to be in and I'm enjoying it."
The stakes will be raised now she has reached the business end of the tournament, with a first-ever meeting against French eighth seed Caroline Garcia looming on the horizon.
However, after three straightforward wins, Keys is fresh and reaping the rewards of a decision to end her 2017 campaign in September to avoid aggravating a left wrist that required surgery at the end of the previous season.
With seeds scattered to the wind in the first week, 2015 semi-finalist Keys has looked serene so far and once she broke Bogdan in the eighth game, she always looked the likely winner.
After breaking early in the second, she was in total command and her only moment of anxiety came when serving for the match at 5-4 as some errors offered up three breaks points.
Keys fended off the danger, though, and completed victory with a punishing forehand that landed right on to the baseline after 73 minutes.
Garcia was one of the most improved players on the women's circuit in 2017 and the Frenchwoman recovered after a mid-match slump to beat Belarusian Aliaksandra Sasnovich 6-3, 5-7, 6-2.
Osaka ends local challenge with Barty beating
Japan's Naomi Osaka overpowered Ashleigh Barty 6-4, 6-2 to reach the fourth round of a grand slam for the first time, leaving the host nation without a contender for the Australian Open women's title.
Barty's quantum leap from the outside the top 200 to number 17 in the world rankings over the last year had given some in Australia hope that the former cricketer might be a contender to end their 40-year wait for a women's champion.
Osaka shredded those hopes in 73 minutes on Rod Laver Arena, breaking Barty to open both sets and combining 12 aces, the last on match point, with 24 winners in a ruthless display of power tennis.
The 20-year-old Japanese, who is ranked 72nd and beat defending champion Angelique Kerber at the US Open last year, will next face Romania's world number one Simona Halep for a place in the quarter-finals.