Fifteenth seed Ashleigh Barty had to dig deep to beat former world number one Maria Sharapova. She held out for the three setters 4-6, 6-1, 6-4 to reach the quarter-finals of the Australian Open on Sunday. Eighth seed Petra Kvitova dispatched young Amanda Anisimova in straight sets 6-2, 6-1 and will face Barty in the quarter-finals.