Djokovic, seeking a record-extending ninth title in Melbourne, was cruising after winning the opening two sets of his third-round clash but a slip at 1-1 in the third set almost derailed his progress.
Daniil Medvedev, the 2021 champion, will need to shake off a run of poor form if he is to mount a challenge.
Nadal appeared close to retiring mid-match but found the will to beat Fritz
Karolina Pliskova warmed up for Wimbledon in the best possible fashion on Saturday by powering past Angelique Kerber 6-1, 6-4 to win the Eastbourne title.
The Indo-Canadian got a walkover in their quarter-final clash against France's Benoit Paire and Stan Wawrinka of Switzerland.
While several top seeds will have their say, a look at some emerging players who could be serious contenders.
Jannik Sinner bounced back after losing the first set to beat Tallon Griekspoor in the third round of the Miami Open.
But Ruud, a semi-finalist last year, stamped his authority in the tiebreak and did not face a single break point in the match as he beat the Canadian for the second time this year.
The Wimbledon men's singles semi-finals take centre stage at the All England Club on Friday.
IMAGES from Day 10 of the Australian Open in Melbourne on Tuesday.
Images from the US Open women's singles quarter-finals at Flushing Meadows on Wednesday.
A summary of the day's tennis action at Roland Garros.
Zheng Qinwen became the first Chinese player to win an Olympic tennis singles gold medal when she held off Croatia's Donna Vekic for a 6-2, 6-3 win in a tense final on Saturday.
Serbia's Novak Djokovic beat Italy's Lorenzo Musetti 6-4 6-2 to reach his first Olympic final on Friday and will bid for gold in a blockbuster clash with Carlos Alcaraz.
The unseeded duo of Bopanna and Shapovalov lost 6-7 (3-7), 6-7 to the Dutch combination of Robin Haase and Wesley Koolhof
Images from the Olympics tennis action at the Roland Garros, Paris, on Wednesday.
Auger-Aliassime, now coached by Nadal's uncle and long-time mentor Toni who sat in his box, will face Fritz in his final group match with a chance of making the last four.
Here is a quick glance of all the highs and lows from Nadal's stupendous career:
Andrey Rublev made the most of Holger Rune's nerves to win a see-saw Monte Carlo final 5-7, 6-2, 7-5 on Sunday, as the Russian's talent was finally rewarded with a Masters title.
Daniil Medvedev quelled the challenge of wildcard Arthur Fery and Marta Kostyuk fought back to upset Maria Sakkari and storm into the Wimbledon second round on a rainy Wednesday.
Raducanu stormed into the third round of the Cincinnati Open
World number one Jannik Sinner's bid for a second Grand Slam title continued to gain momentum as he thumped Christopher O'Connell 6-1, 6-4, 6-2 on Saturday to reach the US Open fourth round.
Holder Stefanos Tsitsipas moved into the Monte Carlo Masters quarter-finals with a 7-5 7-6(1) victory over Laslo Djere
Earlier, title holder Borna Coric beat American Sebastian Korda 7-6 (5), 6-4, while another home hope Taylor Fritz survived a first-set thriller to beat Czech Jiri Lehecka 7-6 (14), 6-2.
Gauff survives scare, Osaka advances
This year's US Open runs from Aug. 28-Sept. 10.
The five-day lockdown, ordered after a new COVID-19 outbreak at a hotel, was due to start at midnight.
Rafael Nadal's hopes of completing a rare calendar year Grand Slam ended on Thursday when the Spaniard pulled out of his highly-anticipated Wimbledon semi-final showdown against Australian Nick Kyrgios with an abdominal strain.
Madison Keys swept past Wimbledon champion Elena Rybakina 6-2, 6-4 at the Cincinnati Open on Friday, setting up a semi-final clash with Petra Kvitova after the Czech defeated Ajla Tomljanovic.
Murray knocked out by Fritz in Washington
Nadal to make injury return at Madrid Open
The Australian was warned for bad language and docked a point for unsportsmanlike conduct after throwing his racquet into the stands during Friday's 6-3, 6-4 defeat by Borna Coric in the Murray River Open at Melbourne Park.
World number one Novak Djokovic eased past Greek Stefanos Tsitsipas 6-3, 6-4 to lift his fifth Dubai Tennis Championships title on Saturday, extending his unbeaten start to the 2020 season. Djokovic has now won 21 straight matches, including 18 this season, having already lifted the inaugural ATP Cup with Serbia and a record-extending eighth Australian Open title last month.
World number one Novak Djokovic was furious with the chair umpire for not suspending play as rain trickled down during his Italian Open second-round match against American Taylor Fritz.
Vasek Pospisil and Denis Shapovalov clinched the winning point for Canada with a 2-6, 6-3, 6-3 triumph over Kevin Krawietz and Tim Puetz in the decisive doubles match.
Coco Gauff rallied from a break down in the final set to beat Swede Rebecca Peterson and reach the Indian Wells quarter-finals for the first time
Zverev's brother Mischa Zverev was also eliminated, going out 6-3, 6-1 to David Ferrer in the first round, while Kei Nishikori eased to a 7-5, 6-2 win over Taylor Fritz to secure a place in the third round.
Big-serving John Isner bid farewell to his professional career after losing to fellow American Michael Mmoh in the US Open second round.
Novak Djokovic and Serena Williams were named men's and women's world champions for 2015 by the International Tennis Federation on Tuesday. The Serb ended the year as men's world number one for the fourth time after taking three majors - the Australian, Wimbledon and US Open, as well as finishing runner-up to Stan Wawrinka in the French. Williams also narrowly missed a calendar-year grand slam, winning the Australian, French and Wimbledon and reaching semi-final at US Open.
Novak Djokovic and Serena Williams were named men's and women's world champions for 2015 by the International Tennis Federation.