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.

No. 19 seed Madison Keys of the U.S. takes on No. 2 seed Iga Swiatek of Poland in a women's semifinal match on Thursday. Check out all the info.

Iga Swiatek is dominating her Australian Open opponents the way no one has at Melbourne Park since Maria Sharapova in 2013.