Novak Djokovic's 30th birthday arrives at a crossroads in the Serbian's illustrious career.
Can Djokovic turn around the slump that suddenly set in during the final year of his 20s or will his greatest moment also prove to be his last great moment?
When he lifted the Coupe des Mousquetaires in Paris last June, Djokovic was on of top of the tennis world in a way no man had been in more than 40 years.
The sun suddenly emerged from behind the thick grey cloud that had obscured it for more than a week, adding natural lustre to a success Djokovic had been chasing for a decade.
Djokovic had not just emulated Roger Federer and Rafael Nadal, he had surpassed them, becoming the first man since Rod Laver in 1969 to hold all four grand slam titles at the same time.
Where was the weakness for his rivals to exploit? Djokovic had closed to within five of Federer's then record of 17 slam singles titles and overtaking the Swiss seemed a real possibility.
It was inconceivable that, a year on, the man who had won 16 of his previous 24 tournaments would not only have failed to add another slam title but would have claimed just two in total while suffering a succession of shock defeats.
All those certainties - his footwork, his backhand, his mind - have spiralled downwards together in a knotty mess that he has so far been unable to unpick.
Perhaps Djokovic's 30th birthday will prove to be the watershed moment he needs.
His decision to part with his long-term team of Marian Vajda - a second father figure - Gebhard Phil-Gritsch and Miljan Amanovic was a drastic move but one that seemed to show that, whatever he is lacking, it is no longer hunger.
Djokovic has been fighting for his place his whole career.
First to move beyond his country's troubles and then to find his own space in the tennis spotlight dominated by two of the most loved players in history.
As Djokovic himself memorably put it, the wolf running up the hill is much hungrier than the wolf standing on top of the hill.
When he finally won the French Open in his fourth final, the wolf not only allowed himself to survey the scene but also realised how tough the climb had been.
Personal troubles took his mind further off the court and the wolves that had been licking their wounds charged up the hill and seized their chance.
Djokovic, meanwhile, moved from wolf to dove, choosing the path of inner peace and love preached by Spanish coach Pepe Imaz.
Imaz remains but the search for on-court enlightenment goes on, and now Djokovic is hunting for a new coach and a voice to help him find his way back to the top.
"I feel like this is a new chapter in my life," he said.
"My career was always on the upward path and this time I'm experiencing how it is when the path takes you in a different direction.
"I want to find a way to come back to the top stronger and more resilient. I am a hunter and my biggest goal is to find the winning spark on the court again."