Noami Osaka will play Karolina Pliskova in the semi-finals of the Australian Open.
Pliskova has beaten Serena Williams in three sets, 6-4 4-6 and 7-5.
Williams had a match point at 5-2, but was called for a foot fault, and then also injured her ankle. She lost six straight games to lose the match.
Earlier, Osaka was an easy straight sets winner over Elena Svitolina.
The other semi features 8th seed Petra Kvitova against the unseeded American Danielle Collins.