The potential championship matchups should bring a lot of intrigue to the first Grand Slam tournament of the year

Swiatek will face No. 19 Madison Keys of the U.S. on Thursday night for a berth in the final. The other women’s semifinal is No. 1 Aryna Sabalenka, the two-time defending champion, against her good friend, No. 11 Paula Badosa.

Keys, the No. 19 seed and a two-time semifinalist at Melbourne Park, had won the first set. But Rybakina, who like Keys is a precise winner machine when she is playing the tennis she wants to play, had taken the second by seizing the initiative and playing on her front foot. Halfway to the finish, Keys had become a passive counterpuncher.