Serena Williams battles over to achieve Australian Open last eight

Serena Williams maintained a strategic distance from an alternate Terrific Hammer vanquish by Spain's Garbine Muguruza as she battled once more to achieve the Australian Open quarter-finals. 

The American world number one, who lost to Muguruza finally year's French Open, passed through 2 6-3 6-2. 

Williams next appearances Slovakia's Dominika Cibulkova, who beat two-time champion Victoria Azarenka 6-2 3 6-3. 

Protecting men's champion Stan Wawrinka and fifth seed Kei Nishikori both won, with Novak Djokovic playing later. 

Wawrinka beat Guillermo Garcia-Lopez 7-6 (7-2) 6 4-6 7-6 (10-8), preceding Nishikori saw off David Ferrer 6-3 6-3 6-3. 

Eighth seed Milos Raonic misused two match focuses in the fourth set tie-break yet recuperated to secure a 6 4 6-3 6 (7-9) 6-3 triumph over Feliciano Lopez. 

American Madison Keys, 19, moved down her win over fourth seed Petra Kvitova by beating countryman Madison Brengle 6-2 6-4, and will confront 34-year-old Venus Williams in the last eight. 

Venus overcame sixth seed Agnieszka Radwanska 6-3 2 6-1 in the night session to achieve her first Fantastic Hammer quarter-last subsequent to 2010.