U.S. Open champion Naomi Osaka has reached back-to-back major finals with a 6-2, 4-6, 6-4 victory over Karolina Pliskova in the Australian Open semifinals.
The 21-year-old Osaka will play another Czech, two-time Wimbledon champion Petra Kvitova, for the Australian title on Saturday.
The champion in Australia will also assume the No. 1 ranking. For both Kvitova, who reached a career-high No. 2 ranking in October 2011, and Osaka, it would be a first time in top spot.
The fourth-seeded Osaka is aiming to be the first woman since Serena Williams to win consecutive major titles. Williams won four straight from the 2014 U.S. Open to Wimbledon in 2015.
Kvitova beat Danielle Collins 7-6 (2), 6-0 to return to a Grand Slam final for the first time since winning the Wimbledon title in 2014, and her first since sustaining injuries to her left hand in a home invasion in the Czech Republic in December 2016.
Seventh-seeded Pliskova, a U.S. Open finalist in 2016, had a stunning quarterfinal win over Serena Williams, coming back from 5-1 down in the third set and saving four match points to reach the last four.
Osaka closed with an ace on match point.
Earlier, John Peers and Henri Kontinen have combined to become the first pair through to the men's doubles final after beating Leonardo Mayer and Joao Sousa 6-1, 7-6 (6) at the Australian Open.
Peers and Kontinen, who combined to win the 2017 Australian Open doubles title, will play either the American team of Ryan Harrison and Sam Querrey or the French combination of Pierre-Hugues Herbert and Nicolas Mahut.
The women's singles finalists will be determined later Thursday. Two-time Wimbledon winner Petra Kvitova was playing Danielle Collins in the first of the semifinals on Rod Laver Arena, followed by U.S. Open champion Naomi Osaka against seventh-seeded Karolina Pliskova.
The first of the men's semifinals will be in the night session, when 17-time major winner Rafael Nadal takes on 20-year-old Stefanos Tsitsipas.
The weather was hot and sunny at Melbourne Park, with the temperature approaching 100 degrees Fahrenheit (38 Celsius).