Golf is a game of trust; trust in your swing, trust in your advisors, trust in your ability,  in your gut.

In that context, Rory McIlroy has the full package. His greatest strength is his self-belief, something that was evident just a month after he turned professional. 

Autograph hunters were lying in wait at the back of the 18th green at Vilamoura's Victoria Course, where he had just finished tied for 58th in the Portugal Masters, thirteen shots behind winner Steve Webster.

"Thanks, Rory," an ex-pat said after 18-year old McIlroy had scribbled on his hat. "This might be worth a few bob if you win a major."

"What do mean 'if'?" McIlroy shouted back over his shoulder as he loped up a slope with that familiar bobbing stride.

Fast forward a decade and McIlroy has four majors and probably feels he should have a couple more. 

When he was asked his greatest strength in Charlotte last week, he looked embarrassed to be asked to blow his own trumpet, then offered this.

"I've never lost faith,” he said. “I think my belief. I have always believed in my own ability from day one. And I still do.”

The question now is whether or not McIlroy truly believes he can play on for another month with a niggling rib problem that leads to a host of undesired side effects.

Not only did he feel some numbness in his left arm after his final round at Quail Hollow, but he also admitted that the pain he feels is leading to bad swing habits.

No wonder former world number one David Duval —a man whose career fell asunder, in part because he lost his swing playing with a back injury— is pleading with him to put the clubs away now before he does himself serious damage.

"He's hurt and I am watching his golf swing deteriorate," Duval said before the final round of the US PGA.

"If only I could go back and tell myself 18-20 years ago when I started having those problems, 'Stop, get healthy'. He could do himself a big service."

While McIlroy is an intelligent man and will sit down later this week with his fitness advisor Dr Steve McGregor to assess his options, he has no problem admitting that stubbornness is one of his strongest character traits.

Should he put the new TaylorMade clubs away until next year and give his rib injury time to heal completely. Or should he play the FedEx Cup playoffs in search of a win or two that might salvage his season?

No doubt TaylorMade and Nike, who recently signed deals with the Co Down man worth a combined $300 million, would love to see their investment on the fairways of the Glen Oaks Club in New York for the first FedEx Cup event in nine days' time.

McIlroy is also the defending champion for the Dell Technologies Championship, scheduled for TPC Boston from September 1-4 and has been promoting the #TeamRorySweepstakes on Twitter, offering the winner the chance to play with him in the pro-am ahead of the third Playoff event, the BMW Championship at Conway Farms.

After three seasons without a major win, McIlroy is in danger of completing his first winless full season since 2008, when he took on Fitzgerald as his caddie.

Last year he salvaged an average year by winning in Boston before snatching the FedEx Cup from Dustin Johnson at the Tour Championship.

But since he won his fourth major in 2014, four players in their 20s have won six of the last 12 majors — Jordan Spieth, Jason Day, Danny Willett and now Justin Thomas.

Several more are waiting in the wings such as Jon Rahm, Hideki Matsuyama, Rickie Fowler, Patrick Reed, Daniel Berger and Thomas Pieters. Dustin Johnson won't be going away anytime soon.

Deciding who will get the lucrative caddying role is a crucial part of the puzzle that McIlroy must try to solve as he looks to 2018 and the run in to the Masters, where he will make his third attempt to complete the career Grand Slam

He looked happy to have his closest friend, Harry Diamond, on the bag in Akron and Charlotte and after admitting that he has been inundated by applications for the job, he must make a decision on that key element of his team soon.

His streaky putting will always be an issue if his long game is anything other than stellar, which makes getting healthy his No 1 priority.

Ranked 74th out of 75 for his play from 50 to 125 yards in the US PGA and 69th for putting, he has issues that need attention.

While it would be a blow to the PGA Tour to lose McIlroy for the FedEx Cup Playoffs and to the European Tour not to have him for events like the Alfred Dunhill Links and the Race to Dubai finale, it may be time for McIlroy to concentrate on his greatest strength — the long game.