Djokovic favourite as 'Big Four' take final bow

The struggles of Murray and Nadal make the longevity of Federer all the more miraculous

The sun may be setting on a golden era of men's tennis but Novak Djokovic's star still burns bright as he returns to Melbourne Park in search of a record seventh Australian Open title.

The doubt-stricken player with a dodgy elbow, who exited early from the last two Melbourne tournaments, has since been replaced by the world-beating Djokovic of old.

Yet the Serb also brings a wiser, harder edge after coming through a period of personal and physical anguish, and breaking a two-year drought at the Grand Slams last year.

The same cannot be said for his 'Big Four' cohorts, who have become progressively worn down by injuries and time after dominating the majors for much of the past decade.

A teary-eyed Andy Murray signalled the Australian Open could be his last professional tournament on Friday, with the pain of his right hip proving unbearable.

Grave fitness fears also shadow 32-year-old Rafael Nadal, the 17-time Grand Slam champion, who pulled out of the Brisbane International warm-up with a thigh strain and had his 2018 season cut short by a string of various injuries.

The struggles of Murray and Nadal make the longevity of double-defending champion Roger Federer all the more miraculous, and even at 37, he may still be the best equipped player to derail the Djokovic train.

Yet, with respect to the Swiss master, 20-time Grand Slam champion Federer swiped the last two Melbourne titles while Djokovic was in the doldrums.

Following his wins at Wimbledon and the US Open, the top seeded Serb is heavily favoured to seal a third successive Grand Slam title, and reclaim a tournament he has virtually owned throughout his career.

Djokovic was only 21 when he upset the defending champion Federer in the 2008 semi-finals, then beat Frenchman Jo-Wilfried Tsonga in four sets to muscle into a Grand Slam club that had become a duopoly between the Swiss and Nadal.

He has hoisted the Norman Brookes Challenge Cup five times since, including a hat-trick of titles from 2011-13, all roared on by Melbourne's big Serbian community.

The world number one suffered a small hiccup in his preparations, upset by Spain's Roberto Bautista Agut in the semi-finals at the Qatar Open.

But he has the luxury of easing into Melbourne against a qualifier before a possible rematch of the 2008 final against French wildcard Tsonga.

On the other side of the draw, sentimentalists will hope third seed Federer and world number two Nadal can grind it out to the semi-finals and reignite the sport's most cherished rivalry.

Others will hope for a long-awaited breakthrough from the next generation, after Federer, Nadal and Djokovic hogged all the Grand Slams last year.

Fourth seed Alexander Zverev might seem the man most likely, having again proved the better of the game's titans with his victory at the season-ending ATP Tour Finals.

However, the 21-year-old talent's quarter-final appearance at the French Open last year is his sole appearance in the last eight at a Grand Slam and he has yet to convince he has the grit and temperament to go the distance in seven matches.