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.
Spaun caps rainy US Open with monster putt for first major title
JJ Spaun drained a 64-foot birdie putt that snaked across a sodden 18th green to win the US Open by two shots from Robert MacIntyre on Sunday as the Californian claimed his first major after a chaotic final round at Oakmont Country Club.
Paris Saint-Germain rolls past Atletico Madrid in CWC play
Fabian Ruiz and Vitinha scored first-half goals and Paris Saint-Germain opened Club World Cup Group B play with a 4-0 victory over Atletico Madrid on Sunday afternoon at Pasadena, Calif.
Russell wins in Canada as McLarens collide
George Russell celebrated Mercedes' first win of the Formula One season in Canada on Sunday while McLaren's Oscar Piastri went 22 points clear in the championship after teammate Lando Norris smashed into him and retired.
Maria crowned first Queen's Club women's champion in 52 years
German qualifier Tatjana Maria capped an incredible week in London as she defeated American eighth seed Amanda Anisimova 6-3 6-4 on Sunday to become the first woman to win a title at Queen's Club in over half a century.
Messi falls just short in Club World Cup curtain-raiser stalemate
Lionel Messi drew vast crowds and showed flashes of his brilliance when his Inter Miami side were held to a goalless draw by African giants Al-Ahly as the revamped Club World Cup got off to a festive start on Saturday.
10:00pm - Midnight
Midnight - 1:00am
