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.

Ben Shelton and Madison Keys became the first American man and woman to reach the Australian Open semifinals in the same year since 2009, with respective quarterfinal triumphs Wednesday in Melbourne.

Ben Shelton reaches his first Australian Open semi-final with a battling win over Lorenzo Sonego in Melbourne.