The resolute, resourceful caddie gets to see the good, the bad and the ugly of this wonderfully humbling pursuit.

Amid all the various visions that can delight or horrify the golfing eye, Michael Greller had not witnessed anything quite like the scenes of Sunday afternoon on Royal Birkdale’s 13th hole as his boss, Jordan Spieth, conjured the best bogey of his career. “It was the greatest by a mile,” declared the American caddie of the flabbergasting finale to the 146th Open Championship. “But I hope I never see one like that again. It was the most bizarre thing I’ve ever experienced as a caddie.”

When you’re heaving the clubs of Spieth, life is never going to be dull. There have been rousing major moments and despairing major meltdowns. It’s par for the course in this topsy-turvy game.

Spieth surpassed himself on Sunday. The elongated, agonising episode, which saw Spieth ponder and pace around between the dunes and the driving range before opting to hit his third shot from the practice ground area, would have mangled the mind of the sturdiest Navy Seal.

“They told me it took 21 minutes,” said Greller of that period of to-ings, fro-ings and rulings. “We’ve been in situations enough where I know, and he knew, just to slow it down. We were not in any rush. We had to find a way to get this back in play and find a way to grind out a bogey. If he makes a double, then he’s still only two back with five holes to go. There was no need to panic. We took our time getting the line, getting the number. He thought it was 270 yards. I thought it was 230. So that was alarming. From my perspective, if it’s short you could work with that all day versus long. I knew he had adrenaline. The up and down was just ridiculous. But that’s what Jordan has always done.”

After that sizeable exercise in damage limitation which injected Spieth with renewed poise and purpose, the 23-year-old turned his fortunes around with a barnstorming blitz as he covered his last five holes in five-under to seize the Claret Jug. “I think it was the most special,” agreed Greller when asked if that was the most magical stretch of golf Spieth has ever produced.

This Spieth and Greller alliance have experienced a lot together. The 2015 campaign saw Spieth win the first two majors of the year and he arrived at St Andrews for the Open in pursuit of the third leg of the grand slam. He would finish just a shot outside the play-off for the title. A few months later, there was the anguish of the Masters blow up.

In the tumult of Sunday, the emotional roller-coaster that Spieth was on was just as intense for the man on the bag.

“For me personally, the (Open) in 2015 hurt more than (the Masters) in 2016, just with what was at stake there,” conceded Greller. “You know how meaningful the Open is. So on Sunday, I was fighting emotions all day out there and having to write things down to remind me to stay in the present. Jordan’s hurt a lot since that 2016 Masters. And I’m sure somewhere in there some doubts had crept in on Sunday. He just said, “you know what, I know how to do this’. Once he made that putt on 13, there was just a different energy in him those last five holes.”

Spieth’s raking putt on the 15th for an eagle was a defining moment too. “That was nothing to do with me,” admitted Greller who was ordered by a pumped up Spieth to retrieve the ball from the hole as he marched to the next tee. “On the shorter putts, he just needed some positive feedback and some affirmation. But those longer ones? That’s just all instinct. I just stay out of his way. He has got the best instincts in the world from that range.”

It’s onwards now to the PGA Championship at Quail Hollow in three weeks where Spieth will be aiming to become just the sixth player to complete the career grand slam.

“There’s no pressure,” he said. “He’s absolutely free-rolling it. He’s going to play in 30 more PGAs during the rest of his life. So what if he doesn’t win it? He’s just won a major.”