It's about to get very noisy on Rod Laver Arena.
The 19-year-old 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, becoming the first Australian man to reach the last eight in the national championship since Lleyton Hewitt in 2005, and the first male teenager since Federer in 2001 to reach two Grand Slam quarterfinals.
He was on a secondary court for his night match, and his first words to a crowd that had chanted and screamed like soccer fans: "Thanks mate. Feels so good."
Murray, a two-time Grand Slam champion and three-time Australian Open finalist, overcame racket-smashing Grigor Dimitrov 6-4, 6-7 (5), 6-3, 7-5 to secure a quarterfinals spot at his 16th consecutive major.
In a 3 1/2 hour-match filled with stunning shots from both players, and which finished after midnight, Murray rallied from 2-5 down in the fourth set to close out against the 23-year-old Bulgarian who has been dubbed "Baby Fed" by those who compare his style with Federer's.
"I did get quite lucky at the end. A few net cords went my way and that was the difference, really," said Murray, who angrily screamed at himself after a double-fault when he was serving for the second set, and again after losing the tiebreaker. "The momentum was switching both ways all the time. Once I got momentum I just tried to keep it going." Dimitrov, who beat Murray at Wimbledon en route to the semifinals last year, shattered his racket by spiking it on court as he dropped his last service game.
Federer went out in the third round — the 17-time Grand Slam winner's earliest exit at the Australian Open in 14 years — in an upset loss to Seppi, who appeared on course to reach the quarterfinals for the first time in 40 majors when he had match point in the fourth set against Kyrgios.
That's when Kyrgios said his own experience kicked in: he'd come back from 0-2 at Wimbledon — he saved nine match points in the second round against Richard Gasquet — where he also beat then-No. 1 Nadal en route to the quarterfinals.
"It's crazy," he said. "When I saw I had finally won the match it was incredible — it was the best feeling I ever had. It's just massive confidence."
Nadal is growing in confidence in his comeback from a long-term injury layoff, with momentum in his 7-5, 6-1, 6-4 win over towering Kevin Anderson swinging 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-tall (6-foot-8) 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 Bernard Tomic.
"The chance to be in the quarterfinals after a tough period of time for me is a fantastic result," Nadal said. "I was playing better than the days before. The way that I improved my level is not the most important thing; obviously the victory is."
No.2-ranked Sharapova won the last eight games of her 6-3, 6-0 victory over No. 21-seeded Peng Shuai to advance to a showdown with Eugenie Bouchard.
Seventh-seeded Bouchard won nine of the first 10 games against Irina-Camelia Begu, but lost seven of the next nine. 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.
"I gave myself a good, long hard look in the mirror," Bouchard said. "I said, 'Genie, this is unacceptable.' I really kind of kicked myself in the butt a little bit."
Bouchard made the semis or better at the first three Grand Slam tournaments last year, losing to eventual champion Sharapova in the French Open semifinals.
Sharapova noted that Bouchard was the most consistent player at recent Grand Slams.
"She's playing really well, confident tennis. So aggressive," the five-time major winner 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 set up a quarterfinal against No. 10 Ekaterina Makarova, who had a 6-3, 6-2 win over Julia Goerges.