After he lost in the quarter-finals at Roland-Garros to Marco Cecchinato, an unseeded player who a week earlier had never won a match in a Grand Slam tournament, Novak Djokovic looked disgusted. When asked what he would do next, he was frank: maybe take a break.

“I don’t know if I’m going to play on grass,” Djokovic said. “I don’t know what I’m going to do. I just came from the court. Sorry, guys, I can’t give you that answer. I cannot give you any answer."

Now, a mere five months later, Djokovic has done the unthinkable. Since that defeat at Roland-Garros, he has lost just two matches and won four titles, including Wimbledon and the US Open. He came within one match of winning the Paris Masters, too, but looked depleted after beating Roger Federer in a classic three-set semi-final. (Karen Khachanov beat Djokovic in the final, ending a 22-match winning streak.)

Djokovic is now the No.1 ranked player in the world, climbing from his low of No.22 as late as June. It’s the first time since Marat Safin in 2000 that a man has become No.1 after being ranked lower than No.20 earlier in the same season.

For Djokovic, the road has been long and bumpy. After winning Roland-Garros in 2016, he suffered from pain in his right elbow. He didn’t win another Grand Slam title that year or the next, and eventually parted company with all his coaches and trainers.

Djokovic received help from Andre Agassi, the American former star, and Radek Stepanek, a long-time friend on the tour. But the pain persisted and Djokovic had to miss the second half of 2017 to rest his elbow.

When the pain returned during the Australian Open this year - a campaign which ended with a straight sets defeat to an inspired Hyeon Chung - Djokovic had surgery.

He wasn’t off the court for long, but his comeback attempt failed to get off the ground. Djokovic lost both matches he played in Indian Wells and Miami. Desperate, Djokovic split with Agassi and Stepanek, and went back to his former crew, led by Marian Vajda.

Vajda’s advice was simple: get back to basics and return to your former form. Djokovic ditched his vulnerable new serve style and began to swing more freely. He won more matches. And even though he was disgusted after his Roland-Garros defeat, Vajda urged him to think positive.

In addition, Vajda had identified Djokovic's physical conditioning and mentality as problem areas, with his team working to build up the Serbian's muscle mass and return him the approach that had reaped such rewards earlier in his career.

"Tennis cannot be based on a philosophy. It's a mano a mano sport. If you want to be at the top, the path is through practice and repetition, playing and a good mentality," Vajda told Slovakian publication Sport.Sk.

There were clear signs that the reunion with Vajda was bearing fruit at Queen's, where Djokovic reached the final and pushed Marin Cilic, one of the favourites for Wimbledon, to three sets.

And then came The Championships itself, where the Djokovic fire of old was reignited in a four-set victory over Kyle Edmund in front of a partisan Centre Court crowd. 

But the true proving ground was a semi-final meeting with Rafael Nadal who, a month after winning his 11th Roland-Garros title, was playing perhaps his best grass court tennis since his run to the Wimbledon singles title in 2010.

But Djokovic rose to the occasion and got off to an incredible start, winning two of the first three sets before the match was suspended at 11pm, already a modern classic in the making.

The next day, Djokovic did exactly what he had done when he won four Grand Slam singles titles in a row: play his best tennis in the most important moments against the toughest opponents.

Though he lost the fourth set, he played his finest tennis in years in the fifth. His serve was crisp. His forehand and backhand were steady, deep and full of remarkable angles.

The fifth set was magic, with both players facing break points and saving them as the match became more intense. At 7-7 in the fifth, Djokovic saved a break point with an exquisite forehand cross court passing shot as Nadal charged the net.

The Serbian raised both of his hands in the air, demanding the crowd's acclaim and feeding off it. He went on to take the set 10-8 in the most stellar match this season, a result which catapulted him towards the Wimbledon, Cincinnati, US Open and Shanghai titles, and the world No.1 ranking.

Djokovic is looking for yet another title this year, at the the ATP Finals in London later this month. Chances are he will at least win enough in London to remain No.1 when the season ends. And then from there, one never knows what might happen. If Djokovic stays healthy, Federer and Nadal’s Grand Slam totals - 20 for Federer and 17 for Nadal - could be challenged.

“I feel like I’m on a whole new level,” Djokovic said after winning the US Open, his 14th major title. “I just like to be here now, you know, work hard, work smart, and thrive.”