No. 1 seed Andy Murray shocked in fourth round of Australian Open

Mischa Zverev of Germany, the world's 50th-ranked player, pulled off the second monumental upset at the Australian Open in three days, stunning world No. 1 Andy Murray of Scotland on Sunday in Melbourne, Australia.

Zverev prevailed 7-5, 5-7, 6-2, 6-4 in 3 hours 34 minutes, using an aggressive style of play and breaking Murray's serve eight times in 21 tries in the fourth-round match.

"I just served and volleyed my way through it," the 29-year-old said after hitting 52 winners and improving to 82-125 lifetime in singles. Zverev came to the net 118 times and won 55 percent of those points.

"It means the world to me," Zverev said. "It's just amazing. I don't know yet how I feel because everything is new to me, and everything feels a little bit unreal."

Murray -- the only man to reach the quarterfinals of all four majors last season -- didn't lose a set in his first three matches prior to running into Zverev.

"Just wasn't meant to be," Murray said. "(Zverev) served very well when he needed to, especially when he was behind in games. Yeah, he deserved to win because he played great when he was down and also in the important moments."

Novak Djokovic of Serbia, the world's No. 2 player, was stunned by wild-card Denis Istomin of Uzbekistan 7-6 (8), 5-7, 2-6, 7-6 (5), 6-4 in Thursday's second round.

Murray lost to Djokovic in the last two Australian Open finals. The two players failed to reach the quarterfinals of the same major for the first time since the 2007 Australian Open.

Zverev meets 17th-seeded Roger Federer of Switzerland or No. 5 seed Kei Nishikori of Japan in the quarterfinals. Zverev is 0-2 versus Federer and never met Nishikori. Federer and Nishikori played later Sunday.

Alexander Zverev Jr., Mischa's younger brother by 10 years and the 24th seed, lost to No. 9 Rafael Nadal of Spain in five sets Saturday in the third round.

In another fourth-round match Sunday, Stan Wawrinka of Switzerland, the No. 4 seed, advanced to the quarterfinals shortly after Murray was ousted with a 7-6 (2), 7-6 (4), 7-6 (4) victory over Andreas Seppi of Italy.

Wawrinka meets Jo-Wilfried Tsonga in the quarterfinals. The 12th-seeded Frenchman defeated Daniel Evans of Great Britain 6-7 (4), 6-2, 6-4, 6-4 on Sunday.

The highest-seed player left on the men's side is No. 3 Milos Raonic, who plays No. 13 Roberto Bautista Agut of Spain in the fourth round Monday.