MELBOURNE, Australia -- Now he's no longer just the kid who upset Rafael Nadal at Wimbledon, he's also the teenager who beat the guy who beat Roger Federer at the Australian Open.

Nick Kyrgios came back from two sets down and saved a match point to beat Andreas Seppi 5-7, 4-6, 6-3, 7-6 (5), 8-6 on Sunday night, becoming the first Aussie to reach the last eight in Melbourne Park men's draw since 2005, and the first male teenager since Federer to reach two Grand Slam quarterfinals.

His first words to a packed Hisense Arena, where the crowd yelled and screamed like football fans: "Thanks mate. Feels so good."

Seppi beat Federer in the third round -- the 17-time Grand Slam winner's earliest exit in Melbourne in 14 years -- and was on course to reach the quarterfinals for the first time in 40 majors.

But 19-year-old Kyrgios had experience in coming back from 0-2 -- he did that at Wimbledon, where he also upset then No. 1-ranked Nadal en route to the quarters.

"I know that he had a lot of confidence, obviously, beating Roger," Kyrgios said. "Drawing all my experience from Wimbledon, coming back from two sets down, I knew I had the legs to do that."

Kyrgios will face the winner of the later fourth-round match between three-time Australian Open finalist Andy Murray and No. 10-seeded Grigor Dimitrov.

Nadal and Maria Sharapova put earlier stumbles behind them with convincing wins to reach the quarterfinals.

French Open champion Sharapova was broken once in the first set before winning the last eight games of her 6-3, 6-0 fourth-round victory over No. 21-seeded Peng Shuai, advancing her to a showdown with Eugenie Bouchard, the most consistent player in women's majors last season.

Seventh-seeded Bouchard won nine of the first 10 games against Irina-Camelia Begu, but lost seven of the next nine to be pushed to a third set for the first time in the tournament.

After serving a double-fault on set point to end the second, Bouchard took a short break before returning to complete a 6-1, 5-7, 6-2 win over No. 42-ranked Begu.

"I gave myself a good, long hard look in the mirror," Bouchard explained of her brief absence from Rod Laver Arena. "I said, 'Genie, this is unacceptable.' I really kind of kicked myself in the butt a little bit."

Momentum in Nadal's 7-5, 6-1, 6-4 win over towering Kevin Anderson swung on two games at the end of the first set. Nadal fended off five break points to hold, and then broke the 2.03-meter (6-foot-8) tall South African's serve to trigger his winning roll. He will next face No. 7 Tomas Berdych, who had a 6-2, 7-6 (3), 6-2 win over local hope Bernard Tomic.

Nadal, who won the Australian Open in 2009 and lost the finals in 2012 and last year, is coming off an extended injury layoff and says he's building as he goes -- thankful he got through a tough five-setter in the second round against U.S. qualifier Tim Smyczek.

"The chance to be in the quarterfinals after a tough period of time for me is a fantastic result," said Nadal. "I was playing better than the days before. I felt myself with better rhythm in the legs, better rhythm with my forehand. The way that I improved my level is not the most important thing; obviously the victory is."

Five-time Grand Slam winner Sharapova, coming off a win in the season-opening tournament in Brisbane, had a hiccup in the second round here when she had to save match points against Russian qualifier Alexandra Panova.

"I feel like something or someone gave me another chance," Sharapova said. "Getting to the quarters is really special."

Bouchard reached the semifinals or better at the first three Grand Slam tournaments last year, and lost in the fourth round at the U.S. Open. Sharapova lost in the fourth round of three majors in a season highlighted by winning the French Open, where she beat Bouchard in the semifinals.

Sharapova said Bouchard was the most consistent player at the recent Grand Slams, and she had to be at her best to beat the 20-year-old Canadian.

"She's playing really well, confident tennis. So aggressive," Sharapova said. "I have a tough match ahead of me, but I always look forward to that."

French Open finalist Simona Halep beat Yanina Wickmayer 6-4, 6-2 to move into a quarterfinal against No. 10 Ekaterina Makarova, who had a 6-3, 6-2 win over Julia Goerges.