The defining factor in Rory McIlroy's return to fitness may not be the player himself, but the man who will devise the plan that will get him back to the top.
As the World No.4 prepares to potentially step away from competitive golf for the rest of the season, behind the scenes Dr Steve McGregor will get to work.
First will be a meeting with McIlroy this week to discuss his options, ranging from playing for the rest of 2017, a significantly reduced schedule or ending his year early.
With the upcoming months dominated by the culmination of both the PGA Tour's FedEx Series and the European Tour's Race to Dubai, the third option seems to be the most likely.
At that point, McGregor comes to the fore. But who is he?
A renowned fitness coach hailing from Liverpool, McGregor has a fairly sizable reputation behind him.
He's drawn up fitness regimes for football clubs across England, most notably Manchester City, Leeds United and Aston Villa.
He was formerly employed by NBA franchise the New York Knicks as a fitness trainer.
Two years ago, the board at the Lawn Tennis Association sought him out personally to try and halt their rapid decline in performances.
Ryder Cup star Lee Westwood credited McGregor with turning around his fitness when the pair first worked together, leading to a surge up the world rankings for the Englishman.
He's been in charge of McIlroy's fitness since 2010, and the Ulsterman admitted in 2012 that he was "a vital part of the team".
Now he has to work his magic again as McIlroy prepares for a critical turning point in his career.
But with McGregor to turn to, there's no doubt he'll be getting the best advice on offer.