Wozniacki upbeat ahead of Australian Open defence

The pain is too much- Murray on brink of retiring

Perhaps even finished on the tour.

Nadal has missed long periods of tennis because of injuries throughout his career, still managing to amass 17 major titles, but has never contemplated a date for retirement. They're both 31 and have birthdays a week apart in May, and they've played each other 36 times at the elite level.

The 31-year-old Murray has been far less fortunate, with major hip surgery a year ago doing nothing to stop the pain that has driven the Scot to distraction and the brink of retirement.

Djokovic did not even appear to be playing quite at full tilt despite losing only two games, but he insisted he was not taking it easy. It's not the way they operate.

"Last year after Australia it took a while until I won a match again, so there are always those sort of silver linings, you could say. I'm confident that I think it needs a good performance by my opponent probably to beat me", said the third seed, who opens his defence against Uzbekistan's Denis Istomin in Monday's night match on Rod Laver Arena.

The 31-year-old's 2012 triumph at the US Open made him the first British male to claim a major title since 1936 victor Fred Perry, who was celebrated with a statue at the All England Club in 1984. I think it would be bad if I changed in three months.

Djokovic has six Australian Open titles, a record he shared with two-time defending champion Roger Federer and Roy Emerson.

Nadal was forced to retire hurt in the fifth set of last year's quarter-final against eventual finalist Marin Cilic, eight years after pulling out midway through his last-eight clash against Murray with a knee injury.

Murray is due to play Spain's Roberto Bautista Agut in the first round of the Australian Open on Monday - a match which may turn out to be his last. But there's unlikely to be another run to the final for Andy Murray, who wants to start the tournament where he has reached the final five times but is unsure how much longer he can play because of the pain in his surgically repaired right hip. We are not 20 any more.

Murray's career is expected to be finished in a matter of months.

"Our trajectory to the professional tennis world was pretty much similar", added the Serb, who faces American Mitchell Krueger in the first round on Tuesday. "Les Petite As". First time we met and played.

"But being honest, when somebody like him, that he achieved nearly everything in his tennis career, is suffering like he's done for such a long time already, and you feel that you are not competitive for the thing that really makes you wake up every morning and go on court with the passion to practice, to improve, and with a goal, then it's so hard, no?"

Djokovic will begin the Australian Open as favourite to take the title for what would be a record seventh time.

"It's sad for me, but for all sport, because Andy is a very respected and likable guy around the locker room", Djokovic said. He's had it all.

"I felt comfortable straightaway when I hit balls on that court".