Reigning champion Madison Keys will confront the first major roadblock of her Australian Open defence when she faces countrywoman Jessica Pegula in a blockbuster round-of-16 clash.
Ninth seed Keys and world No.6 Pegula's all-American showdown will kick off the action on Rod Laver Arena on Monday - with compatriots Amanda Anisimova, Taylor Fritz and Ben Shelton also in last-16 action.
