Stunned Murray follows Djokovic out of Melbourne tournament

World number one Andy Murray suffered a huge fourth round upset to 50th-ranked Mischa Zverev to follow Novak Djokovic to the exit as the shocks kept rolling at the Australian Open on Sunday.

Murray was never expected to be troubled by the 29-year-old German, who has never won an ATP title, but he lost 7-5, 5-7, 6-2, 6-4 in his earliest Melbourne departure in eight years.

Zverev's serve-volley triumph blows the draw even wider open with the top two seeds out before the quarter-finals for the first time in a Grand Slam since the 2004 French Open.

Among the beneficiaries could be Roger Federer, who plays Kei Nishikori later, and Rafael Nadal, who downed Zverev's younger brother Alexander in a titanic five-setter on Saturday.

Alexander, 19, was watching courtside as Zverev stretched to a series of elastic volleys to halt the nonplussed Murray. Nearly half of Zverev's points were from serve and volleys.

"I was like in a little coma, just serving and volleying my way through it. There were a few points where I didn't know how I pulled it off but somehow I made it," Zverev said.

With the defeat, Murray extends his curse at the Australian Open, where he has been runner-up five times -- losing four finals to Djokovic -- without lifting the trophy.

He also makes the earliest exit for an Australian Open top seed in 14 years, since Lleyton Hewitt fell at the same stage in 2003.

"I've had tough losses in my career in the past. I've come back from them. This is a tough one," Murray said.

"I'm sure I'll come back okay from it. But right now I'm obviously very down because I wanted to go further in this event, and it wasn't to be."

'Big surprise'

Zverev, a late bloomer after a career riddled with injuries, reaches his first Grand Slam quarter-final where he will play his idol Federer or Japanese fifth seed Nishikori.

Meanwhile Stan Wawrinka, who won the first of his three Grand Slam titles in Melbourne in 2014, came through 7-6 (7/2), 7-6 (7/4), 7-6 (7/4) against Italy's Andreas Seppi.

The formidable Swiss, now into his fourth Australian Open quarter-final, will play France's Jo-Wilfried Tsonga, who came from a set down to beat British surprise package Dan Evans, for a place in the semis.

He said Murray's defeat showed that even the top players can't take victory for granted.

"It's a big surprise for sure. It shows that it's not so easy as we can think, or when we see the draw, to just win, keep winning all the time," Wawrinka said.

Earlier Venus Williams, the oldest player in the women's draw at 36, also became one of the first into the quarter-finals when she beat German qualifier Mona Barthel 6-3, 7-5.

The seven-time Grand Slam winner allowed herself to dream of a possible final with her sister Serena, who is steaming through the other side of the draw in search of her 23rd major title.

"That could hopefully happen. We both still have to work very hard to get there," Venus Williams said.

Her quarter-final opponent is Anastasia Pavlyuchenkova, who beat fellow Russian Svetlana Kuznetsova 6-3, 6-3 to reach her first Australian Open quarter-final in nine attempts.