When Novak Djokovic won the French Open in June 2016, the sky appeared to be the limit for the then world number one. The Serbian had dominated tennis during the previous season, reaching the final in all but one of the 16 singles events he entered, winning 11 titles including three grand slams; all this before he clinched the year-end world number one ranking for a fourth time.
Roger Federer's record of 17 major titles was within touching distance when Djokovic won a record-equalling sixth Australian Open crown and then added the elusive French Open to his trophy cabinet. Djokovic became the eighth player in history, and fourth since 1999, to complete the set and ensure his name would remain inscribed in the history book of the sport for generations to come.
But since that crowning moment at Roland Garros, the world surrounding Djokovic seems to have come crashing down around him. The 29-year-old is now a stark contrast of the player who struck fear into all who dared to cross him; a man mountain at the back of the court who was ready to re-write the history of men's tennis. IBTimes UK documents his remarkable turn of fortunes, the latest chapter of which was written in shocking fashion at the Australian Open.
Aced out of SW19 by Sam Querrey
Having overcome Murray in Paris, Djokovic was the strong favourite to retain his Wimbledon title as the tour reached the green, green grass of SW19. James Ward and Adrian Mannarino were dispatched in straight sets, without alarm, to set the defending champion on his way.
But in round three he was served out of the tournament by the big-hitting Sam Querrey, who struck 31 aces in completing a four-set win over Djokovic and ended his hopes of a calendar grand slam. Sergiy Stakhovsky, Dustin Brown and Lucas Rosol had all vanquished previous champions in recent years, adopting a game which overpowered their opponents so there was no initial reason for concern for Djokovic, given the manner of his exit.
First round elimination at the Olympic Games
Victory at the Rogers Cup in Canada without dropping a set had initially calmed any fears Djokovic was set for an insipid second-half of the campaign, but that was all to change at the Rio Olympics. A patriotic Djokovic had shed tears of joy eight years earlier when winning bronze at Beijing 2008 but there were emotions of a different kind in Brazil last summer.
Up against Juan Martin del Potro, who was making a comeback from a second bout of wrist surgery, Djokovic was dominated from the outset. The Argentine needed just two sets to progress from the round-one clash and would end up pushing Murray all the way in the singles final before claiming silver. Djokovic was notably distraught, yet could be forgiven after being paired with a former grand slam champion.
US Open final defeat to Stan Wawrinka
The cracks in the Djokovic armoury were there for all to see en route to the US Open final, where he was defeated by Stan Wawrinka, as the Swiss' grip over the number one seed tightened. On his way to the final at Flushing Meadows, Djokovic became increasingly irate at his inconsistent displays and ripped his shirt in anger during his semi-final win over Gael Monfils.
Prior to the tournament, the reasons behind Djokovic's slump finally began to become apparent. Speaking ahead of the final grand slam of 2016 in New York, Djokovic admitted "some other thing that I was going through privately" had contributed to his premature exit at Wimbledon. Furthermore, a wrist injury was blamed for hindering him in the defeat to Del Potro in Rio.
But aside from Djokovic's physical shortcomings, many media outlets had identified a possible issue between him and wife Jelena, who was seen sitting away from his players' box during his matches at America. Fans also speculated on various online forums, including Reddit, that Djokovic had engaged in an off-court affair with their nanny, though such suggestions have neither been confirmed nor denied by the player's camp.
Loses world number one to Sir Andy Murray
The only crumb of comfort for Djokovic remained that he was still expected to end the season as the world number one, for what would be a fifth time. But his titles at the Masters 1000 events in Shanghai and Paris both slipped away, with Roberto Bautista Agut and Marin Cilic benefitting from his downward spiral.
Before being dethroned in the French capital, Djokovic admitted for the first time that lack of motivation had been a factor in his recent decline in form. Victory on the Paris clay earlier in the year had complete the career grand slam and left Djokovic empty and without purpose. "I felt a little bit exhausted, I must say, and maybe less motivated," he conceded.
To assist with his mentality, Djokovic made another addition to his rapidly growing and changing coaching team in the form of spiritual guru Pepe Imaz. Maybe not confirmation that Djokovic was growing desperate over his ebbing invisibility, or perhaps even senile, but the move certainly highlighted his discontent with his current set-up.
Meanwhile, Murray staged an assault on the summit of men's tennis with a 24-match winning streak that won him five titles in a row, including at the ATP World Tour Finals for the first time, to help him end the year as the world number one; the first Briton to do so. In the final at the season-ending tour finals he beat Djokovic in a one-sided clash which highlighted how the confidence had drained from the 2010 Davis Cup winner.
Knocked-out of Australian Open by world number 117
Djokovic split with coach Boris Becker after three years with the German, and remains without a full-time replacement. Nevertheless, he returned to winning ways in Doha at the Qatar Open as he beat Murray in the final and arrived at the Australian Open as the favourite to claim a record seventh title, and third in a row.
Fernando Verdasco troubled Djokovic during their first round encounter but was unable to sustain his form. Wild-card Denis Istomin was then expected to be sent packing, but the world number 117 rallied after losing the opening set and after going within two points of victory in the fourth set tie-break, secured the win in dramatic fashion in the decider.
While defeat strengthens Murray's grip on the world number one ranking, it now leaves Djokovic at the lowest point of his career since he announced himself on the world stage by winning in Melbourne in 2008. Magnanimous and gracious in defeat to the Uzbekistan player, Djokovic has been left disconsolate by the result which sees his campaign start in the worst possible fashion.
What is next?
Though Djokovic is very much the hunter in the battle with Murray, he has it all to do when the ATP Masters Series schedule starts at Indian Wells and then Miami in March and April, having won both titles last year. The clay court schedule may come to his rescue at the right time before he attempts to win a second French Open in Paris.
But perhaps the biggest challenge for Djokovic will be in conquering the demons which have affected him since completing the career grand slam. Coming back from his recent collapse and regaining the mantle as the main man in men's tennis would arguably rank as one of his finest achievements, but one he must realise to ensure his legacy does not become tarnished.