Naomi Osaka won the first set against the 54-ranked American, Madison Brengle, 6-0.
After the impressive opening, it looked like the Japanese were heading for a clear victory.
But in the second set, Brengle invited to dance.
The American went up to a 4-3 lead in the second set and shook the reigning champion.
But Osaka got up and after three straight paper clips, she secured the ticket to the third round.
- I was very good in the return game today.
It is not usually my strongest side but it helped me today, she says after the victory.
In the third round, new American opposition is now waiting in 60-ranked Amanda Anisimova.
If there is a win there, the world setter and home favorite Ashleigh Barty will probably wait in the fourth round.