The women’s top seed refuses to blame an unspecified back injury for her loss

Novak Djokovic crushed Fabio Fognini while Ana Ivanovic upset Serena Williams to complete a winning Serb double as the Australian Open reached the midway point on Sunday.

Djokovic was ruthless in his 6-3, 6-0, 6-2 demolition of Fognini, who can inspire and frustrate in equal measure.

Against the second seed, he looked barely interested after Djokovic got on top from the start and stayed there.

“I’ve felt from the start of this tournament that I’ve been elevating my game, every match is better. The general feeling on the court, all the shots, using the court position really well, being aggressive, playing my style of the game,” the Serb said.

“That’s what I’ve done really well today overall from the first to the last point. I haven’t allowed my opponent to come back to the match,” said Djokovic.

He scored 33 winners and four breaks of serve in just over 90 minutes to move into his 19th straight Grand Slam quarterfinal.

Swiss eighth seed Stanislas Wawrinka used an afternoon practise session with Roger Federer to best advantage as he hammered Tommy Robredo 6-3, 7-6 (7-3), 7-6 (7-5).

It set up a re-run of last year’s epic fourth-rounder against Djokovic won by the Serb 12-10 in the fifth set.

Ferrer, Berdych progress

Spanish third seed David Ferrer continued his quiet march through the draw, beating German Florian Mayer 6-7 (5-7), 7-5, 6-2, 6-1. Tomas Berdych defeated Kevin Anderson for a ninth time, 6-2, 6-2, 6-3.

Ivanovic reversed a career-long loss streak against Williams to send the injured top seed out in the fourth round 4-6, 6-3, 6-3.

Ivanovic lost the opening set for her ninth on the trot against Williams before turning on the afterburners to pave the way for the win in a shade under two hours.

“Going on to the court today, I really just tried to give my best,” said the winner, world number one in 2008 after winning the French Open. “I tried to make it a good match.

“I was very competitive till the last moment, and I’m just very thrilled, obviously. I actually believed, I had some confidence coming into the match.

“I really did certain things extremely well, and kept her under pressure throughout the whole match.”

“I almost didn’t play her, but at least I’m proud that I tried the best I could these last couple of days,” Williams said.

China’s fourth seed Li Na advanced over Russian Ekaterina Makarova 6-2, 6-0 while Italian veteran Flavia Pennetta upset German ninth seed Angelique Kerber 6-1, 4-6, 7-5.

Eugenie Bouchard became the first Canadian in 22 years to reach the quarterfinals of a slam when she beat Casey Dellacqua 6-7 (5-7), 6-2, 6-0.

More In: Tennis | Sport