On June 5th 2016, Novak Djokovic reached the top of the mountain.
Victory over Andy Murray in the French Open final saw him become the first man since Rod Laver in 1969 to hold all four Grand Slams titles at once.
It has been largely downhill since.
An elbow injury has taken its toll on the former ‘Iron Man’ with some high-profile coaching changes failing to spark a revival.
Rise, then fall
In 2015, Djokovic had one of the greatest years in tennis history.
He was 82-6 for the season with only Stan Wawrinka denying him a calendar Grand Slam in the French Open final.
Djokovic reached 15 consecutive finals and won a record six Masters 1000 titles from eight finals.
2016 started in much the same way as he beat Murray to join Roy Emerson on six Australian Open titles.
He continued to dominate and secured his first title at Roland Garros, becoming the eighth man in history to win all four majors.
But his Wimbledon defence ended in a shock third-round exit to Sam Querrey with Djokovic later alluding to “private issues” affecting his game.
Then his dreams of Olympic gold were wrecked in the opening round at Rio 2016 by Juan Martin del Potro.
The man from Belgrade looked to have found his mojo again at the US Open, but Wawrinka beat him in the final at Flushing Meadows.
He then failed to reach the finals at Shanghai and Paris, with double Olympic champion Murray displacing him as world number one after four consecutive tournament victories.
Murray ended 2016 in style with a resounding win over Djokovic in the final of the ATP World Tour Finals in London.
And the Serb split with coach Boris Becker who claimed his charge had lost focus after the French Open.
“He didn’t spend as much time on the practice courts in the past six months as he should have. And he knows that. Success like this doesn’t happen by pushing a button.” – Boris Becker talking to Sky Sports after parting ways with Novak Djokovic
Djokovic gained revenge on the Briton in the Doha final at the start of 2017.
He arrived in Melbourne fancied to claim a seventh Australian Open crown, but world number 117 Denis Istomin stunned him in five sets.
Splits and injuries
After further struggles, Djokovic ditched his backroom team in April 2017 including long-time coach Marian Vajda.
He brought in Olympic champion and tennis legend Andre Agassi, but was humbled by Dominic Thiem in the quarter-finals at Roland Garros, before retiring in the second set of his Wimbledon quarter-final against Tomas Berdych.
Afterwards, the Monaco resident revealed he had been struggling with an elbow injury for the previous 18 months.
“My elbow is hurt due to excessive playing, and it troubles me constantly when serving, and now when playing forehand as well.” – Novak Djokovic in July 2017
He took the rest of the year off, returning just in time for this year’s Australian Open.
In the last 16 in Melbourne, Djokovic went down in straight sets to Hyeon Chung before undergoing minor surgery on that troublesome elbow.
He returned to the tour in early March and failed to win a match at either Indian Wells or Miami.
Djokovic then cut ties with Agassi and Radek Stepanek, reuniting with former coach Vajda.
He did manage two victories on home clay at Monte Carlo before Thiem knocked him out in three sets.
But this week, he fell at the first hurdle to 140th-ranked qualifer Martin Klizan.
The cause and the cure
So where has it all gone wrong?
Djokovic’s athleticism, durability and mental strength made him the best player in the world.
Now he has suffered his first major injury since reaching the top, and the cracks have appeared.
The wear and tear on his elbow has clearly affected him, and that aura of invincibility he once had has vanished.
“I just ran out of gas. I am trying, but it’s not working. It’s impossible at the moment.” – Novak Djokovic after his Miami Masters defeat to Benoit Paire
While Djokovic has endured his slump, Roger Federer and Rafael Nadal have bounced back to their best.
And Federer said in March that he believes his old rival can return to his peak.
“When you come back from injury or when you haven’t played in a long time, it just takes extra effort. It is still early stages for Novak coming back. He’s only going to get better from here.” – Roger Federer on Novak Djokovic’s Indian Wells exit.
Djokovic looks unlikely to make an impact at Roland Garros next month.
And in the long term, there is a chance this tennis great may never return to his brilliant best.