- New research claims a caddie can help boost a golfer's performance by 30% or more
- Four important pillars of relationship built around closeness and commitment
- Padraig Harrington credits caddie Ronan Flood with winning him the 2007 Open
- Tiger Woods won 13 of his 14 major titles with caddie Steve Williams on his bag
You are the one hitting the shots, but the man standing over your shoulder could hold the key to your golfing destiny.
A caddie can often be dismissed as just an accessory whose sole role is to lump a golfer's clubs round the course and occasionally throw a few speculative blades of grass into the wind.
But new research by a leading university suggests a caddie could prove the difference between success and failure.
So when the world's best golfers line up for 2014's final major at the U.S. PGA Championship, take a moment to study the person by their side.
"It's simple. In 2007 my caddie Ronan Flood won me the British Open," said three-time major champion Padraig Harrington.
The Irishman, who won the U.S. PGA Championship in 2008, had a one-shot lead coming down the 18th at Carnoustie in Scotland as he battled to claim his first major back in 2007.
But then the nerves took over.
"I hit my tee shot in the water on 18 and was despondent, I then hit my third shot into the water again and felt like I'd lost," he explained.
"I had to walk about 150 yards for my next shot and Ronan was talking to me, coming out with all the cliches about what to do next.
"For the first 50 yards I wanted to strangle him, for the next 50 yards I started listening to him and for the last 50 yards I believed him.
"I was in the zone, then out of it and then back in it again -- that really doesn't happen very often.
"In that moment of time I do believe Ronan made the difference -- with any other caddie I would have thought I had lost but my caddie believed in me.
"It's all about creating your own reality when you're on the golf course."
Harrington's recovery from that double blow secured a playoff with Sergio Garcia that he would go on to win, and the 42-year-old retained his British Open crown the following year.
His relationship with Flood was critical in that glut of success, underlined by a pair of YouTube videos to support the study in which Harrington's caddie helped him hole a shot from 150 yards while blindfolded.
That was part of the research commissioned by HSBC and carried out by Loughborough University, which says a good caddie can boost a golfer's performance by 30% or more.
According to Dr Sophia Jowett, the Director of Research Degrees at Loughborough, the axis between player and caddie must be built around four central pillars.
First is closeness, including trust and respect, commitment, being complementary as well as open and co-orientation, which hinges on shared knowledge and understanding.
Those qualities are, of course, allied to the nuts and bolts of the job.
Any caddie must know the game and their employer inside out, study the course and the wind conditions, have food and water available, as well as be able to tell the odd joke here and there.
But fundamentally, according to the top players, you just need someone you get on with.
"We're like brothers, brothers that Mom and Dad left alone -- and they left him in charge," Ted Scott previously told CNN of his relationship with two-time Masters champion Bubba Watson.
"Sometimes I just want to punch him, but I love him. And I know he feels the same about me. But don't let anybody else say anything bad about us. We'll go into battle for each other."
Watson notoriously wears his heart on his sleeve while out on the course, and his maverick approach to the game often sees him attempt shots other pros wouldn't even contemplate.
A case in point is the shot that set up his first Masters victory in 2012, as he somehow managed to maneuver the ball onto the green from a position deep in the trees of Augusta's 10th hole during a playoff with Louis Oosthuizen.
So how does Scott keep Watson's emotions in check?
"It takes a long time to learn someone. And that's the art of caddieing -- you have to learn your player," Scott says. "For Bubba it's about keeping him in the middle emotionally.
"You don't want him to get too excited, or too mad. He's extremely emotional. It's about trying to watch him and getting back to that middle point where he plays his best."
One of the most potent player-caddie relationships of recent times was between Tiger Woods and Steve Williams.
The Kiwi was on the bag for all but one of Woods' 14 major titles, and the 38-year-old hasn't claimed another since they parted ways.
Williams is now right hand man for Australian Adam Scott, who grabbed his first major title at The Masters in 2013, fulfilling years of potential.
"If caddies are just carrying the bag, then players would just hire a local caddie," Williams told the PGA Tour.
"Every player requires different things -- the most important role is basically getting your man around the course best you can.
"You have to have the best understanding of the course all the time so you can try to prevent errors.
"There are always going to be errors, but caddies can give the right information and prevent a lot of errors. But we all know the player hits the shots."
The ultimate pressure might be on the player, but there are a few examples of a caddie only adding to their stress levels.
Miles Byrne was caddying for 1991 Masters champion Ian Woosnam at the British Open in 2001 when he realized he had 15 clubs in the bag rather than the permitted 14.
Woosnam, who was in contention for the title at the time and eventually finished third, hurled the offending club into the rough when Byrne informed him of the error and sacked him a few weeks later.
Thankfully, there were no such dramas this time round.
Playing in his first major championship during this year's tournament at Royal Liverpool was home favorite John Singleton.
The factory resin worker thought his chances of a pro career had vanished after injury curtailed his progress as a youngster but took his place at Hoylake through a qualifying tournament -- a victory he put down in large part to assistance from his caddy Ally Haddow.
"He's the reason I was at The Open. He did a top notch job when I qualified," Singleton told CNN, prior to teeing off at Hoylake.
"He knows it's an emotional week for me, he's fantastic at controlling my emotions -- that's his main job.
"If I hit a bad shot it is my responsibility because I'm the one who hit it. If we're not sure what shot to hit we talk it out until we are happy with it. That builds trust really quickly."