We were walking the back nine when the text came. O’Hair is out, Wolstenholme is in. This had implications.

The veteran amateur Gary Wolstenholme had no caddie arranged and 5 Live had said that if it came to it, we would help out.

BBC man caddie's for Wolstenholme

That meant either reporter Andrew Cotter or me taking on the bag duties.

In the end it came down to footwear. Cotter was the only one wearing caddie-issue trainers and they would need to be pressed into action for an afternoon practice tee time.

So we belted back from the 13th tee – we could not have been further from the clubhouse - to meet Wolstenholme and the deal was done. Cotter was hired.

Next, he went to register as a US Open caddie. He returned clutching a bag of freebie goodies that included everything from energy bars, towels, sun cream to nail clippers.

Then, having nearly forgotten his sunglasses, Cotter was off for the practice round donning a rather faded 2005 5 Live golf cap.

Cotter is emulating his brother Colin in caddying at a major championship. He has twice been a bagman at the Open and had a brief spell carrying Colin Montgomerie’s bag.

It will be arduous work on this spectacular course. If you watch on television you won’t be able to fully appreciate the steep drops and climbs involved.

They are at their most severe on the 614-yard monster 13th where a new tee has been built close to the cliff edge, with the Pacific Ocean as the backdrop to this rollercoaster hole.

Phil Mickelson, who grew up on this course, hates this new tee. "It’s the biggest waste of money that I’ve ever seen. It’s terrible.

"Before there was a great risk and reward. Now from that back tee no one can reach it. Everybody is going to be laying up to the same spot and everybody is going to be hitting the same pitch.

"There is no opportunity for a guy who wants to take a little bit of a risk and try to get it to the green (in two) and be rewarded."

The approach to the green is steeply uphill and the target is a small plateau that will demand the utmost accuracy.

If you were asked to identify the lone Northern Ireland competitor here, you would be tempted to think of a Darren Clarke or a Graeme McDowell.

But in fact the America-based Chris Devlin is the only Ulster representative after coming through a US qualifier.

Devlin wants tough conditions this week. He said: "I hope the wind blows like hell. I want it to play as hard as it can possibly play. It’s the only chance I’ve got."

A survivor of open heart surgery, Devlin contrived to break his three wood on the range on the eve of the championship. It was on his second swing that the club broke at the hosel.

"It had nothing to do with my strength," Devlin said. "I’m just glad it happened here and not on the course."

It has been a big week for 20-year-old American Jordan Cox. Not only is he playing the US Open for the first time, he also got to practise with Tiger Woods and Bubba Watson.

"Tiger’s hitting it great," Cox reported. "Buba’s not hitting it quite as good as Tiger, but close. Both of them made me feel really comfortable."

Cox’s week isn’t just all about golf. On Tuesday night he was doing a Stanford University communications exam online. It was a three-hour paper.

A far tougher examination waits for him and his 155 fellow competitors over the coming four days.