With no standout favourite in the women's field, it could provide an ideal stage for American Serena Williams to finally end her quest for an elusive 24th Grand Slam title.
Thirteen-time champion Rafael Nadal, 20-time Grand Slam winner Roger Federer and world number one Novak Djokovic were placed in the same half of the French Open draw on Thursday.
Osaka will play Jennifer Brady for the title.
Three-time US Open champion Djokovic, who comes into the tournament having won his fifth Wimbledon title, is followed in the seedings by 2017 winner Rafael Nadal.
American Serena Williams has also said that the dropouts will not take the shine off a potential record-equalling 24th Grand Slam title for her.
Serbia's Novak Djokovic has beaten Andy Murray to the International Tennis Federation's (ITF) annual men's World Champion award with American Serena Williams taking the women's prize for a third time.
The 2013 Wimbledon finalist Sabine Lisicki set a new world record.
Maria Sharapova continued her untroubled progress at the Qatar Open on Friday, brushing aside Australia's Samantha Stosur 6-2, 6-4 to reach the semi-finals.
Factbox on American Serena Williams, who won her 15th Grand Slam singles title at the US Open on Sunday with a 6-2, 2-6, 7-5 win over Victoria Azarenka of Belarus.
American Serena Williams reached the semi-finals at the WTA Tour Championships in Istanbul on Thursday with what is fast becoming a routine defeat of World No 1 Victoria Azarenka.
American Serena Williams powered her way to a fifth Wimbledon singles title with an explosive start and a cool finish after a mid-match meltdown to beat Poland's Agnieszka Radwanska 6-1, 5-7, 6-2 on Saturday.
Novak Djokovic will begin his Australian Open title defence against Frenchman Jeremy Chardy, while reigning women's champion Sofia Kenin meets wild card Maddison Inglis, following the draw for the year's first Grand Slam on Friday.
Former world number one Serena Williams has pulled out of the French Open because she has not fully recovered from health issues, organisers said on Thursday.
Denmark's Caroline Wozniacki was named top seed of a grand slam tournament for the first time on Tuesday for the US Open starting next Monday.
Caroline Wozniacki became the first Danish tennis player to be crowned world number one when she beat Czech Petra Kvitova 6-3, 6-2 to reach the quarter-finals of the China Open on Thursday.
Sam Stosur became the first Australian woman in 38 years to win the U.S. Open when she upset American Serena Williams 6-2, 6-3 on Sunday in an ill-tempered final.
Bianca Andreescu is the first Canadian to win a major in the professional era.
American Serena Williams dropped a large hint that she could soon be back on court competing when she posted an Instagram photo of a pair of dazzling gold and white tennis shoes.
Women's tennis appears to be in good shape despite the sight of the world's best players limping across the finishing line in Doha last week, where the WTA Championships often resembled a dance of the walking wounded.
The equation could not be simpler: whoever performs best out of Russian Dinara Safina and American Serena Williams at next week's WTA Championships in Doha will end the year as world No 1.
American Serena Williams barged her way into the second round at Wimbledon on Monday with a 6-1 7-5 victory over Portuguese qualifier Neuza Silva.
Fourth seeded Williams beat Serbian second seed Jelena Jankovic in straight sets to win her third US Open crown and ninth Grand Slam title.
Justine Henin qualified for the WTA Championships semi-finals with a 6-2, 6-2 win over Jelena Jankovic.
American Serena Williams was third time lucky as she finally equalled Steffi Graf's long-standing record of 22 Grand Slam wins after defeating Germany's Angelique Kerber 7-5, 6-3 in the Wimbledon final on Saturday.
Britain's Johanna Konta faces an anxious 24-hour wait before discovering whether she will make her debut at the WTA Finals in Singapore.
Maria Sharapova remained on course for consecutive Madrid Open titles when she recovered from dropping the second set to beat Caroline Wozniacki 6-1, 3-6, 6-3 on Thursday and book a spot in the semi-finals.
American Serena Williams withdrew from the French Open on Monday, shortly before she was due on court to face Maria Sharapova in a much-anticipated fourth round showdown.
In a rematch of their tumultuous 2018 US Open decider, Osaka underlined her status as the new queen of women's tennis and soaked up the cheers from the Rod Laver Arena crowd as fans returned to the Grand Slam after a five-day lockdown.
Osaka, 20, shot to international fame on Saturday when she defeated 36-year-old American Serena Williams at Flushing Meadows to become the first Japanese player to claim a Grand Slam singles crown.
As Russian Maria Sharapova and American Serena Williams get ready to slug it out in their big-ticket semi-final, records and history tells us who has had the upper hand.
The US Open has said it regrets that French player Alize Cornet was given a warning for removing her shirt during a match following complaints that the decision was sexist.
Key facts and records of American Serena Williams and Canada's Bianca Andreescu
Following is a list of American Serena Williams' 22 grand slam singles titles as she equalled Steffi Graf's professional era record with victory at Wimbledon on Saturday
Steady rain hit the US Open on Monday, washing out the last match on Arthur Ashe Stadium court featuring five-time champion Roger Federer.
World number one Serena Williams slammed Shamil Tarpishchev for using "extremely sexist, racist and bullying" comments after the Russian Tennis Federation (RTF) president described her and sister Venus as the "Williams brothers".
A golden moment for Australian Ashleigh Barty and American CoCo Vandeweghe was tinged with disappointment when tournament officials did not let them speak to the crowd after winning the U.S. Open women's doubles final on Sunday.
The 30-somethings have enjoyed themselves at the French Open this year and American twins Bob and Mike Bryan continued the trend by winning a record-extending 14th Grand Slam doubles title at Roland Garros on Saturday.