Rafael Nadal, Naomi Osaka and Milos Raonic are the high profile names to opt against playing at Wimbledon which starts 28 June.
The 30-year-old Canadian missed the French Open this year and had not played since the Masters 1000 in Miami in March
Novak Djokovic says it's a "gamble" to keep playing the Australian Open and his abdominal injury could have an impact on the rest of his season, but the world number one is prepared to take the risk.
World No 1 Ashleigh Barty said it was "very strange" to play behind closed doors, a day after more than 22,000 fans visited Melbourne Park, as the five-day, state-wide lockdown went into force.
Australian Open 2021: Tournament boss Craig Tiley plays down fears of Novak Djokovic pulling out due to injury
The ailing Serb somehow came though an gruelling five-setter on Friday night against Taylor Fritz, overcoming an abdominal "muscle tear" that cast doubt over whether he will be able to continue.
Australian Open 2021: Serena Williams, Naomi Osaka sail into second round; Angelique Kerber, Gael Monfils out at first hurdle
Venus Williams, on Monday, won a Grand Slam match for the first time since 2019.
Zverev had to dig deep for his 6-7 (5/7), 6-3, 7-6 (7/4) win to seal the tie, but gained valuable court time ahead of another crack at a first Grand Slam trophy at the Australian Open starting next week.
ATP Cup 2021: Novak Djokovic makes perfect start with win over Denis Shapovalov; Dominic Thiem suffers defeat
Djokovic showed no signs of being hindered by a nasty blister on his racquet hand that troubled him at an Adelaide exhibition last week and returned 30 minutes later alongside Filip Frajinovic to play the decisive doubles rubber.
Medvedev was on top form in a high-quality encounter, winning 5-7, 6-4, 6-1 to secure his first trophy of the season and the eighth of his career.
Paris Masters 2020: Alexander Zverev beats Rafael Nadal in straight sets to set up final against Daniil Medvedev
The German claimed his second successive win over Nadal in impressive fashion, easing to a 6-4, 7-5 victory after Medvedev's earlier 6-4, 7-6 (7/4) win over Milos Raonic.
Nadal, who claimed his 1,000th career victory by beating Feliciano Lopez on Wednesday, is bidding for a first Paris indoors triumph which would draw him level with Novak Djokovic on a record 36 Masters titles.
Paris Masters 2020: Rafael Nadal romps to 1000 Tour-level wins; Diego Schwartzman inches closer to ATP Finals debut
The 28-year-old Schwartzman was too strong for France's Gasquet, taking a 7-5, 6-3 victory, and will next face Spanish qualifier Alejandro Davidovich Fokina in the last 16 at Bercy Arena.
Humbert, who is on a seven-match winning streak after winning the Antwerp title last month, missed four match points but battled to a 7-6 (7/4), 6-7 (6/8), 7-6 (7/3) victory.
Wawrinka won the last of his three Grand Slam titles at the 2016 US Open but was then hit by multiple injuries and is now ranked 20th in the world.
Italian Open 2020: After US Open run, Shapovalov piling up wins in Rome, Azarenka double bagels Kenin
After spending more than 22 hours on court over the previous two weeks at the US Open, where he reached the quarterfinals in both singles and doubles, Shapovalov is still going strong after crossing the Atlantic.
Italian Open 2020: Teenager Lorenzo Musetti stuns Stan Wawrinka; Garbine Muguruza beats Sloane Stephens in straight sets
Stan Wawrinka, the 10th seed in Rome, lost 6-0, 7-6 (7/2) against a player ranked 249th in the world.
US Open 2020 Men's Preview: Novak Djokovic's title to lose; potential first-time winners abound in draw
Novak Djokovic is the overwhelming favourite to win the US Open, which starts on 31 August, with multiple players hopeful of lifting their first Grand Slam trophy.
Western & Southern Open: Novak Djokovic clinches record-equalling 35th Masters title by beating Milos Raonic
Novak Djokovic tied Rafael Nadal’s record by earning his 35th title at a Masters 1000 tournament, overcoming a sluggish start to beat Milos Raonic in the Western & Southern Open final.
Among the areas the PTPA would look into, according to the email: ATP and tournament rules and regulations, revenue sharing, disciplinary actions, pensions, travel, on-site food and amenities, insurance and medical care.
Western & Southern Open: Naomi Osaka withdraws from semi-final in protest, tournament 'paused' for a day
Naomi Osaka tweeted that as a Black woman, she feels compelled to pull out of the tournament to put a focus on police shooting Black people.