Unseeded American Amanda Anisimova saved two match points to stun the former world number one 4-6, 6-3, 7-6 (10/5) in third round match.
Osaka, winner of the 2019 and 2021 Australian Opens, has vowed to have more fun on court this year, following a difficult last year in which she said she had suffered from depression.
Defending Japanese champion Naomi Osaka has beaten Colombian rival Camila Osorio with 6-3, 6-3 and reached the second round of the Australian Open.
The defending Australian Open champion pulled out of the match at a WTA tournament in Melbourne with an abdominal injury, allowing her opponent Veronika Kudermetova to advance to the final on a walkover.
Officials gave no reason for the world no 1's decision to pull out of WTA India Wells singles’ draw, which was already suffering from the absence of several top-ranked players, including Naomi Osaka and Serena Williams.
Naomi Osaka has struggled for form after withdrawing from French Open in May after a row with tournament officials over required media appearances.
World number one Ash Barty crashes out of US Open, losing 6-2 1-6 7-6(5) to 43rd-ranked American Shelby Rogers, in biggest upset of tournament thus far.
Naomi Osaka's title defence was over in third round with a 5-7, 6-7 (2), 6-4 loss to Leylah Fernandez, an 18-year-old from Canada who is ranked 73rd and never had been this far in Grand Slam competition.
World number 2 Osaka cruised through the first set and looked like she would make short work of the Swiss wild card but soon Teichmann swung the momentum firmly in her favour.
Osaka, who has a Haitian father and Japanese mother, said she plans to do more In addition to donating prize money from the Western & Southern Open tennis tournament to relief efforts in Haiti, where a 7.2 magnitude quake killed over 1400.
The events of the Olympics are a big change from what people of Colour, including athletes, have historically been forced to do: pursue a road of stoic fortitude to perform.
US gymnast Biles withdraws from individual all-around competition at Tokyo Olympics, a day after shocking the world by pulling out of the team event that Russia won.
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