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.
David Beckham knighted for services to sport and charity
David Beckham, one of Britain's most celebrated football players, was knighted by King Charles at Windsor Castle on Tuesday, recognising his decades-long contribution to sport and charitable causes.
Aryna Sabalenka challenges Nick Kyrgios in Dubai showdown
Tennis fans are in for a treat this December as WTA World No. 1 Aryna Sabalenka takes on showman Nick Kyrgios in a one-off exhibition match, Battle of the Sexes: The Dubai Showdown.
Dubai Basketball continues unbeaten home run with win over Partizan
Dubai Basketball continued its perfect start in the ABA League with an 82:70 victory over Partizan in Round 5.
Sunderland's Xhaka earns draw after Ndiaye's stunner for Everton
Iliman Ndiaye scored a superb solo goal for Everton but Granit Xhaka's deflected equaliser secured a deserved point for Sunderland in their entertaining 1-1 Premier League draw at the Stadium of Light on Monday.
Rybakina enters semis, Anisimova beats Keys in WTA Finals
Elena Rybakina qualified for the WTA Finals' last four, beating an error-prone Iga Swiatek 3-6 6-1 6-0 on Monday, while Amanda Anisimova beat fellow American Madison Keys 4-6 6-3 6-2 in Riyadh.
