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.

Madison Keys is back into the Australian Open semifinals for a third time after her 3-6, 6-3, 6-4 win Wednesday over Elina Svitolina of Ukraine.