The World number one beat Croatian Donna Vekic 6-3 4-6 7-6 (7-4) at the Porsche Tennis Grand Prix.
Osaka will now face Anett Kontaveit, who was able to progress after Victoria Azarenka retired.
Petra Kvitova will face Kiki Bertens in the other semi-final.
Top contender Sabalenka faces fresh scrutiny at Wimbledon as mental scars linger
Aryna Sabalenka will carry the aftershocks of yet another Grand Slam meltdown into Wimbledon as the world number one comes under heightened scrutiny to show her nerve holds when the pressure spikes on the sport's biggest stage.
Munoz strike sends Colombia into World Cup Round of 32
Daniel Munoz has fired Colombia into the World Cup Round of 32 on Tuesday, sealing a 1-0 win over DR Congo in Group K after goalkeeper Lionel Mpasi had threatened to turn the match into a night of frustration.
Qatar's sports minister, Madibo visit Canada's injured Kone
Qatar's sports minister, Sheikh Hamad bin Khalifa bin Ahmed Al Thani, and national team player Assim Madibo have visited Canada midfielder Ismael Kone to check on his health after he was injured during their World Cup game, the Qatar Football Association said on Wednesday.
Budimir gives Croatia win to eliminate Panama in Group L
Ante Budimir has guided Croatia to a 1-0 win over a stubborn Panama side in their World Cup Group L clash on Tuesday, giving the Balkan side a crucial three points and eliminating the Central Americans on a night where the stakes were high for both sides.
England fail to break down Ghana in goalless draw
England has failed to find a way through a resolute Ghana side and had to settle for a 0-0 draw in their second World Cup Group L match on Tuesday.
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