Intro:

Flavia Pennetta, Li Na, Eugenie Bouchard, Novak Djokovic, David Ferrer and Tomáš Berdych all progressed to the Australian Open quarter-finals on Sunday.

Script:

The fourth round of the Australian Open began on Sunday.

In the women's side of the draw, 28th-seed Flavia Pennetta of Italy shocked world number nine Angelique Kerber of Germany by winning two sets to one.

China's Li Na made light work of her Russian opponent Ekaterina Makarova; 6-2, 6-0.

Canada's Eugenie Bouchard responded to the scare of losing the first set tie break against home favourite Casey Dellacqua by winning the next two sets and only dropping two games.

Over to the men's matches now and world number two Novak Djokovic flexed his muscles with this ace and a straight sets success over Italy's Fabio Fognini.

Last year's Australian Open winner will face either Stanislas Wawrinka or Tommy Robredo in the quarter-final.

34 places separate Florian Mayer and Spaniard David Ferrer in the world rankings but it was the German underdog who took the first set tie break.

But Ferrer showed his class to win 3-1.

Tomáš Berdych of the Czech Republic had no such problems against South African Kevin Anderson, who was defeated in straight sets.