Tennis: Azarenka denies title defence eased by upsets

Victoria Azarenka insisted Monday the upsets of Serena Williams and Maria Sharapova did not make the job of defending her Australian Open title any easier as she blasted into the last eight.

World number one Williams and third seed Sharapova were both fourth-round casualties, leaving the Belarusian well-placed to become the first woman to win the title in three consecutive years since Martina Hingis between 1997-99.

But the 24-year-old said there were plenty of possible roadblocks ahead.

"It doesn't matter," she said of the tournament drawcards' demise.

"We still have high competition out there. The players who beat those players deserve all the credit because they've been better, so they are dangerous and they are competitive.

"For me it's important to just keep focusing on my game and play it one at a time. Quarter-finals of a Grand Slam is never easy, no matter who you play."

Despite her comments, Azarenka is now the player to beat after racing past young American Sloane Stephens 6-3, 6-2 to set up a quarter-final with fifth seed Agnieska Radwanska or exciting young Spaniard Garbine Muguruza.

She is yet to drop a set and appeared to be peaking at the right time as she stretched her winning streak at Melbourne Park to 18 matches.

"I just go out there and play my best, because anybody on any given day -- we've seen that happen in the last couple days -- can bring their best game," she insisted, when asked if she was now favourite.

"You have to stay alert. It doesn't matter the level, that you're number two or whatever. Everybody has proven that anybody can beat anybody.

"The way I approach the matches, I have to be ready 100 percent for every player."

It was her first meeting with 20-year-old Stephens, the 13th seed who is yet to win her first title, since their controversial last-four clash here in 2013.

During that match, Azarenka walked off court for a medical timeout after Stephens had saved five match points and broken the Belarusian.

She returned after a slow handclap from the crowd and Stephens won only three more points, losing 6-1, 6-4 and leading to accusations of gamesmanship from some quarters.

Azarenka later said she had been troubled by a rib injury.

Before Monday's match the pair insisted any hostilities were in the past, although Stephens admitted their relationship was "non-existent".

At one point Monday Stephens hit a ball straight at Azarenka's body, but the Belarusian shrugged off the incident.

"That's tennis. I'm just focused on the next point," she said. "Maybe she had an open court, but she chose that shot. I have no problem with that. I'm just focused on the next one."

Azarenka, nicknamed "Vika", comfortably held her first service game, as did Stephens, who has had a consistent Grand Slam record over the past year, reaching at least the fourth round on each occasion.

Despite Azarenka firing two double-faults in her second service game, Stephens was unable to capitalise and she paid the price when her serve was broken in the fourth game on a wayward backhand.

The defending champion's probing returns and pinpoint baseline shots were troubling Stephens, who had to dig deep to save six break points in the sixth game.

But she was unable to get the break back as Azarenka kept the pressure on to take the set.

Stephens' confidence was being sapped by the relentless second seed, who scored another crucial break in the first game of the second set and there was no way back as Azarenka sped away for the win.