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.

That's why Keys, 29, has surprised herself with her improbable run in the ongoing Australian Open. After defeating Elina Svitolina 3-6, 6-3, 6-4 to clinch a semifinal berth on Wednesday, Keys burst into tears while putting her career in perspective.

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.