Roger Federer says he will win the tournament one day but, as Andy Murray headed out of Melbourne Park last night, he will be kicking himself that he didn’t make the most of what had become a big opportunity to add to his tally of three grand slam titles.

His 7-5, 5-7, 6-2, 6-4 fourth-round defeat by Mischa Zverev, a 29-year-old German ranked No.50, who had lost in the first round in 13 of his 17 previous grand slam events, ended his hopes of a first Australian Open title.

“I'm obviously down about it,” he said. [But] it’s just tennis. I had great success for a number of months. Obviously in the biggest events you want to do your best. Obviously that's not been the case here. It happens.

“I've had tough losses in my career in the past. I've come back from them. This is a tough one. I'm sure I'll come back OK 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.”

The second-round defeat of six-time champion Novak Djokovic, who beat Murray in four of the Scot’s five finals, left many thinking world No.1 Murray’s name was already on the trophy.

Murray knew that was far from the case, not least with Stan Wawrinka, Federer, Kei Nishikori and Jo-Wilfried Tsonga all in his section of the draw, and the likes of Rafael Nadal and Milos Raonic in the other half.

“There are certainly no guarantees, even if I got through today's match, that I would have gone further,” Murray said. “It's disappointing to lose. I don't feel like this is any more of an opportunity than other years.”

He had been in this position before, not least at Wimbledon last summer, where he went on to win the title for a second time.

But while he knew he had tough battles ahead, Murray would never have expected to have lost to Zverev, a man he beat easily when they met last spring.

That, though, was on clay and Zverev, whose career was interrupted for three years by injuries, has been rejuvenated by the arrival on the world scene of his younger brother Sascha, who had pushed Nadal so hard in the previous round.

But it was the manner in which Zverev took the attack to Murray, and the unbelievable quality with which he did it, which left the Scot constantly on the back foot and took him out of his comfort zone.

The left-hander served and volleyed brilliantly and when Murray served, he took his returns so early and drilled them so deep that the Scot found it hard to pass him.

In all, Zverev came to the net 118 times, winning 65 of them, and forced Murray into numerous errors just by the sheer fact he was coming forward and then by his ability to play some beautiful, smart volleys.

It is a throwback to the 1980s, when John McEnroe and later Boris Becker and Stefan Edberg stormed into the net at every opportunity.

Murray, perhaps the best counter-puncher in the world, was rushed throughout but he had a chance to win the first set, failing to serve it out at 5-3.

Having let slip an early break in the second, he managed to win it but from then on he was always behind, unable to find enough passes and more importantly, get free points on serve, with Zverev all over his second serve.

And while he got a little excited when he closed in on victory, Zverev held his nerve to clinch the win of his career, setting up a quarter-final with Federer, who beat fifth seed Kei Nishikori in five sets.

“I knew there was no Plan B really,” he said, of his all-out attacking game. “I can't stay on the baseline, a couple feet behind the baseline, try to out-rally him. He's very strong physically. He has a good baseline game.

“I knew I had to come in. That was my only chance to win. I’d played him a few times before, when we were young, but I knew I could get to him with my game, play some slice, try to annoy him and it worked.”

Zverev had wrist surgery two years ago and said the progress of Sascha, now ranked 24, helped him believe he could get back into the top 100. He’ll now be ranked 35.

Djokovic’s loss had already ensured that Murray will remain world No.1 for a good while yet, with a 1,715 point lead in hand before his next tournament.

Having lost in the second round at the Indian Wells and Miami Masters 1000s last year, tournaments won by Djokovic, the chances are that by the start of the clay-court season, he could be around 3,000 points ahead.

His next assignment is due to be for Britain in the Davis Cup in Canada, the week after the Australian Open is completed, although Murray was non-committal.

“I don't know what I'm going to do immediately,” he said. “I’ll have a chat to my family first. Didn't get to see loads of them at the end of last year with training and then going over to Doha and stuff. First people I'll speak to is them, see what I do.

“Davis Cup would be next on the schedule. But whether I stay here or go home in the meantime, I'm not sure.”