By Greg Stutchbury
MELBOURNE, Jan 20 (Reuters) - The dominant duo of Maria Sharapova and Novak Djokovic are both aware they need to build on their already impressive form as they look to gain quarter-final berths at the Australian Open on Sunday.
Sharapova, who recorded 6-0 6-0 victories in her first two rounds, demolished seven-times grand slam champion Venus Williams in the third round on Friday and meets Belgian Kirsten Flipkens on Rod Laver Arena, still looking to improve.
"I think the reason I started so well in this tournament is because I knew that I had to," Sharapova said in reference to her entering the grand slam without playing a competitive match.
"Considering I didn't play any matches, I'm happy with my form. But, like I said, I'm always looking to improve. That's always my goal."
Sharapova and Flipkens have met just twice before, with the Russian winning both matches, though the last time they played was at Roland Garros in 2010.
"I think this is the best slam that she's done, right, fourth round?" Sharapova asked.
"She's a tricky player, uses her slice really well, and a good athlete as well; moves around the court quite well.
"It's an opponent I really have to look out for.
Djokovic has also not been stretched in his three matches so far, though his clash with Radek Stepanek was the most entertaining match of the tournament.
He has won the last 10 encounters against Wawrinka, including clinching their last match in the fourth round at last year's U.S. Open when the Swiss retired suffering from dizziness.
Former world number one Ana Ivanovic also faces a daunting task against Poland's Agnieszka Radwanska, who is in the midst of her career-best winning streak.
The 23-year-old world number four is on a 12-match win streak and has already clinched two titles this year in Auckland and Sydney with her patient, finesse game that contrasts with the brutal power of the top three.
"She has style of game that doesn't give you much and you really have to work for your points," Ivanovic said.
"Being patient is going to be a key. It's going to be tough, for sure. I have to be prepared to work hard for my points and to keep on putting pressure on her."
Men's number four David Ferrer also continues his quest for his first grand slam against Japan's Kei Nishikori, who has a 2-1 career record against the Spaniard and beat the retrieving baseliner at last year's London Olympics. (Editing by Patrick Johnston)