Top seed and two-time defending champion Novak Djokovic advanced to the fourth round at the Australian Open on Friday.

The three-time overall Aussie Open titlist became the first man to reach the round of 16 at this 2013 fortnight with a 6-4, 6-3, 7-5 victory over Czech Davis Cup hero Radek Stepanek at Rod Laver Arena.

"Well, yes, definitely," Djokovic said when asked if this was his toughest match thus far. "I mean, I wasn't expecting an easy match coming into the third round and playing a seeded player; somebody that has a lot of experience playing on the tour."

The Serbian star broke the 31st-seeded Stepanek once in each set and fired 37 winners en route to victory, his seventh straight against the Czech veteran and 17th straight overall in Melbourne.

At Djokovic's post-match news conference, the questions quickly went from tennis to another sports star -- Lance Armstrong -- who confessed about doping in cycling during a television interview with Oprah Winfrey.

"I think it's a disgrace for the sport to have an athlete like this," Djokovic said. "He cheated the sport. He cheated many people around the world with his career, with his life story."

Djokovic, who beat Rafael Nadal in last year's epic final and also won the title at Melbourne Park in 2008, is bidding to become the first three-peat champion in the Open Era at this Grand Slam event. He will next play Swiss slugger Stanislas Wawrinka, the 15th seed who straight-setted 20th-seeded American Sam Querrey 7-6 (8-6), 7-5, 6-4. The 6-foot-6 Querrey was the last American standing in the draw.

Meanwhile, gritty fourth-seeded Spaniard David Ferrer, fresh off his title in Auckland last week, whipped 28th-seeded 2006 Aussie Open runner-up Marcos Baghdatis 6-4, 6-2, 6-3 and fifth-seeded former Wimbledon runner-up Tomas Berdych trounced helpless 26th-seeded Austrian left-hander Jurgen Melzer 6-3, 6-2, 6-2. Berdych lost just nine of his first-serve points and struck 12 aces en route to the round of 16.

Up next for Ferrer will be 16th-seeded rising Japanese Kei Nishikori, while the formidable Czech Berdych will meet tall South African Kevin Anderson in the fourth round.

Other winners Friday were Djokovic's eighth-seeded countryman Janko Tipsarevic, 10th-seeded Spaniard Nicolas Almagro, Nishikori and Anderson.

Tipsarevic rallied to beat 32nd-seeded Frenchman Julien Benneteau 3-6, 6-4, 2-6, 6-4, 6-3 and reach the fourth round Down Under for the first time in his career. In doing so, he joined Djokovic as the second-ever Serb to reach the round of 16 at all four major events.

Up next for Tipsarevic, who improved to an impressive 17-8 in his career five-set matches, will be Almagro, the sweet-swinging Spaniard who topped towering 24th-seeded Pole Jerzy Janowicz 7-6 (7-3), 7-6 (7-4), 6-1.

Nishikori advanced with a 7-6 (7-3), 6-2, 6-3 triumph over Russian Evgeny Donskoy. Last year, Nishikori became the first Japanese man to reach the quarterfinals in Melbourne in the Open Era.

Anderson, meanwhile, fought back to oust 22nd-seeded Spanish southpaw Fernando Verdasco 4-6, 6-3, 4-6, 7-6 (7-4), 6-2. Anderson is the first South African man to reach the fourth round at a Grand Slam event since Wayne Ferreira reached the Aussie Open semifinals back in 2003.

The surging Anderson was a runner-up in Sydney last week.

The third round will conclude on Saturday, including matches for second-seeded former world No. 1 and four-time Aussie Open champ Roger Federer and third- seeded reigning U.S. Open titlist Andy Murray. The reigning Wimbledon champ and 17-time Grand Slam king Federer will meet capable 20-year-old Aussie Bernard Tomic, while Murray will battle Lithuanian Ricardas Berankis. Murray was the back-to-back Aussie runner-up in 2010 and 2011.

In some other third-round action on Day 6, sixth-seeded former U.S. Open champion Juan Martin del Potro will take on Frenchman Jeremy Chardy; seventh-seeded 2008 Aussie Open runner-up Jo-Wilfried Tsonga will play Slovenian Blaz Kavcic; ninth-seeded nifty Frenchman Richard Gasquet will be opposed by Croat Ivan Dodig; and 13th-seeded Canadian star Milos Raonic will encounter 17th-seeded German Philipp Kohlschreiber, last week's Auckland runner-up to Ferrer.