No. 19 seed Madison Keys scored the big upset on Day 9 of the Australian Open, defeating No. 6 Elena Rybakina 6-3, 1-6, 6-3 at Margaret Court Arena to advance to the tournament quarterfinals.

The No. 6 seed missed multiple break points to seize the advantage in the third set and Keys profited to move into the quarterfinals.

Elena Rybakina, the sixth seed at Melbourne Park, had looked in fine form in the early rounds, but came into Monday's clash with Madison Keys at Margaret Court Arena carrying a back issue

Elina Svitolina rallied from 4-1 down defeat Veronika Kudermetova 6-4, 6-1 to reach the Australian Open quarterfinals. Svitolina will face Madison Keys in the next round.

Madison Keys has upset former runner-up Elena Rybakina to set up an Australian Open quarter-final with inspired veteran Elina Svitolina.