A man who defines undemonstrative, Dustin Johnson barely raises a smile when he wins.

So when the world No. 1 fist pumps a par save at the opening hole – that’s right, the first hole – the penny drops. These US Opens are savage.

To eulogise this tournament’s brutality – to hear it always branded in battle-like terms – is approaching cliché on our side of the pond.

Is the rough really that thick? Are the greens really that slick? We watch on TV and yawn as commentators reach for the superlatives. We’re inured to expect exaggeration.

But I’ve seen things today – things that send a shudder through my 11-handicap heart.

I winced as Rory McIlroy hit a shot that should never be seen outside of a Saturday morning medal.

US Open

I watched Tiger Woods rack up a triple bogey from the middle of the fairway.

His putting stroke, the once silky smooth pendulum that helped win 14 major championships, twitched like he was possessed.

I saw a former British Amateur champion fail to break 90.

And I listened as a whole gallery of fans cheered wildly – all because a player merely managed to hold a green.

This is a stunning course but the devil takes on many disguises. I’ve seen golfing hell. Its name is Shinnecock Hills.

To think some were worried about how low the morning scores might be.

The rain that saturated the course on Wednesday afternoon was supposed to assist the early starters.

But for Justin Rose, whose 71 was a textbook of grind and graft, any such optimism evaporated the moment he got out of his car.

“I’m like whoa, what’s going on?” he said. “The wind, the flags, were already fluttering dead straight. So I knew I was in for a tough day when I saw that.”

By the time Scott Gregory finished off a 92, the highest score since Felix Casas suffered the same fate at Bethpage Black 16 years earlier, the field were already averaging 5-over.

There were more bogeys than pars on the par 3 second, a 252-yard monster that was playing half a shot higher.

That still paled in comparison to 14, where more than two dozen of the field suffered double bogey or worse.

Shinnecock can make a fool of you – striking without cause or warning.

US Open

Standing only 100 yards away on the 10th, Justin Thomas was eyeing a three. He finished with six.

The second best player in the world looked humbled, an expression bordering on bewilderment etched across his face, as he first chunked a chip before overcompensating and sending a missile over the back.

He then hit his fourth into the bank, only for it to trickle back to his feet.

I felt only empathy. I knew exactly what he was going through.

“They’re difficult,” said Ian Poulter when trying to sum up the sadism of the US Open experience.

“They’re hot. They’re stressful. It feels like you’re pulling teeth every single hole you play.”

US Open

McIlroy, meanwhile, may want to reassess what he sees as fun golf. I don’t think a 10-over 80 met the criteria.

The TV cameras were replaying a bunker shot on the 16th, a mishit that banged into the summit of the trap and barely found its way out, as the defining moment of his first day failure.

But the Northern Irishman’s helplessness in the face of the gusting winds and ever quickening greens was better explained on the first when a low scud was all he could muster out of the fescue.

From a similar lie, Tiger almost took out a spectator on the 14th. This grass takes no prisoners.

And finally a sombre warning, from one who lived to fight another day.

“The golf course is firming up as the week’s going on,” warned Masters champion Patrick Reed following his 73.

That’s a scary thought. It’s only going to get harder.

We’re going to need those helmets after all.