Outside of family, Michael Bannon has been the constant figure in the Rory McIlroy success story, which saw Major number four secured in the early hours of Monday morning.
Bannon has been McIlroy's guiding light from the earliest days and was the first person the 25-year-old phenomenon embraced at Valhalla when the US PGA title was safely tucked away.
Bannon preaches simplicity and, from the age of seven, McIlroy has followed that doctrine – and this summer's form has been stunning after spells of self-doubt and periods of inconsistency .
McIlroy now requires few adjustments to the swing itself and his game is simply majestic.
"If it ain't broke, don't fix it," McIlroy said.
"That's my motto. I've always been that way.
"I feel that the work that I put into my swing between the ages of 15 and 20 is going to see me through my career.
"I know the parameters of it, and I know how to get it back on track.
"I've worked with Michael Bannon my whole life. Whether it is to try to get even better or look for a new challenge, I'll continue to do so," added the Holywood ace.
McIlroy has benefitted greatly from the calm, straightforward counsel of Bannon.
Bannon's strategic nous could be glimpsed in both of McIlroy's victorious final rounds in Majors this summer. Sandwiched between those was another stunning triumph – at the WGC Invitational at Akron.
Whether in 18 holes of careful containment, protecting an initial six-shot lead as at the Open at Royal Liverpool, or in the outrageous audacity of his 281-yard three-wood to eight feet for eagle at the 10th at Valhalla, he reflected his coach's advanced understanding of when to attack and when to defend.
"Our relationship has changed over the past few years," McIlroy explained.
"Now it's about course management. He was a fairly accomplished player himself, so I have good chats with him about picking certain shots for certain situations."
Having cultivated his own craft on the Kirkistown Castle links, buffeted by the squalls of the Irish Sea, Bannon has a cerebral approach to impart, born of often harsh experience.
He contended in the 1998 Irish PGA Championship, ultimately losing in a play-off to 27-year-old Padraig Harrington, before abandoning the tour dream for a career of more understated duties at Bangor Golf Club.
But from the second the young Rory pitched up at his door, with a seemingly innate capacity for holding his posture through impact and turning his right shoulder towards the target, his own star rose.
Eventually, and only after helping to guide McIlroy to those startling eight-shot wins in the 2011 US Open and 2012 PGA, did he accept the call to assume the role full-time.
Such are the stresses of having a global celebrity as employer that Bannon can often be non-committal about McIlroy on the record, but it pays to recall his remark after the victory at Congressional three years ago.
Bannon said: "I feel very honoured to have been able to coach this guy to where he is now, but I'm also very humble about it.
"Rory owns his swing. He hits the shots."
A compelling reason why McIlroy shows Bannon such unswerving loyalty lies in this very humility – a coach who will seek not to take advantage of him, or to divert the spotlight to himself, but simply to advise.
Amid all the hurtling changes in his life Bannon remains the hardiest perennial, arguably the man he needs most of all.
McIlroy is currently taking a week off, during which he will be a special guest at Manchester United's clash with Swansea at Old Trafford, before returning to action next week ahead of next month's Ryder Cup at Gleneagles.
Bannon may not make it to Old Trafford on Saturday when the world number one will be introduced to the crowd.
But you can be sure he will be a key figure as McIlroy looks to add even more lustre to his sparkling season.