Serena Williams displayed all her fighting qualities to make it to the quarter-finals in the Australian Open today, but two-time champion Victoria Azarenka was bundled out. World number one Serena beat the 24th seeded Spaniard Garbine Muguruza 2-6, 6-3, 6-2. She will next face last year's finalist Dominika Cibulkova, the 11th seeded Slovak. World number one Novak Djokovic takes on unseeded Gilles Muller of Luxembourg in Men's singles later today.