Novak Djokovic stands on the brink of a record-equalling 22nd Grand Slam title and it is his determination to be the greatest ever which drives him on through the controversies.
The 35-year-old Serb is already one major clear of Roger Federer and victory over Stefanos Tsitsipas in the Australian Open final on Sunday will draw him level with Rafael Nadal.
For Djokovic, it matters to be the best and he has a strong sense of his historical place in tennis.
But he also keeps ploughing on through the highs and lows because it is "a great school of life".
"I play professional tennis for several different reasons," he said in Melbourne.
"Some personal reason is that I feel on the tennis court I always have an opportunity to learn something new about myself, I guess fight with my own demons that I guess we all have.
"When we're on the tennis court in the midst of a battle, some of the things surface, and I have to deal with it, so it's a great school of life for me.
"Then at the same time, of course, I have professional goals and ambitions," he added. "Those are Grand Slams and being number one in the world.
"So I do want to make more history in this sport, no doubt."
- Brooding, divisive -
But while Federer and Nadal are widely admired, Djokovic continues to divide as well as unite, despite being one of the greatest players to grace tennis.
His staggering achievements on court have often been overshadowed by blunders and missteps off it.
The latest was his father posing with a Russian flag featuring Vladimir Putin's face at this year's Australian Open.
But easily the most controversial was his refusal to get vaccinated against Covid, which culminated with Djokovic last year being deported from Australia on the eve of the tournament.
Even before that, the Serb was seemingly doomed never to be held in the same esteem as Federer or Nadal, the undisputed people's champions.
There are those who see something too calculating in the Djokovic make-up -- an intense, brooding presence prone to affectation.
His infamous default from the US Open in 2020 for petulantly swiping at a ball that hit a female line judge gave a glimpse of his fiery character.
And some of his personal stances have drawn criticism -- one claim that raised eyebrows was his belief that it was possible to alter the composition of water and food through positive thinking.
- 'Rock-steady' -
However, the career achievements and resolve of a player who was the first to smash through the $150 million prize-money barrier cannot be doubted.
Djokovic, who left Belgrade when he was 12 to train in Munich and escape NATO's bombardment of his home city, has won 21 Grand Slam titles in his career haul of 92.
He captured the first of his majors at the Australian Open in 2008, but it was three years before he added his second.
He dropped gluten from his diet, his lithe physique allowing him to chase down lost causes, transforming him into the rubber man of tennis with a rock-steady defence.
In 2011 he enjoyed a spectacular year, winning three of three Slams and becoming world number one for the first time.
In total, he has nine Australian Opens, seven Wimbledons, three US Open titles and two French Opens.
And time appears to be on his side in the quest to be considered the greatest of all time.
Federer is now retired while Nadal, 36, is again struggling with injury, crashing out of this year's Australian Open in the second round as defending champion.
Djokovic shows few signs of losing his physical edge, but knows the clock is ticking.
"I don't know when the end is going to happen in terms of professional career," he said on Friday.
"Right now I have the motivation, I have support of the close ones, which is also something that is probably underestimated and not maybe talked about a lot, but it's key, especially as a father."
Djokovic married long-time girlfriend Jelena Ristic in July 2014 and they have two children -- a son, Stefan, and daughter, Tara.