Watch: The best and worst of the US Open after one round

We knew going into the 2016 US Open that Oakmont is probably the hardest course in golf, so we're fully prepared for carnage over the next four days.

What happened to Jordan Spieth and Jason Dufner during a rain-shortened first day in Pittsburgh was just brutal, though.

Spieth hit an approach shot into the par-4 from 116 yards out and landed it near the middle of the green, spinning it back by the hole and seemingly earning a shot at birdie.

But the ball kept spinning back, picked up a slope on the green and ended up rolling all the way into a greenside bunker. Spieth couldn't believe it, and the TV broadcast picked up his reaction:

"You gotta be kidding me! How is that that in the bunker? That is such crap!"

Dufner needed to get up and down from the fairway to save par on the 18th hole at Oakmont, but he got an awful break on an approach shot that should have left him with a short putt.

He hit a 40-yard approach that bounced once on the green short of the flag, then smashed the back edge of the cup and ricocheted backwards 30 yards, nearly coming back to his feet.

A few centimetres shorter and the ball would have landed inside the cup for a birdie, but instead Dufner had to essentially replay the same shot.

Dufner's third shot travelled a net distance of just 10 yards, and he left his fourth shot 19 feet from the cup.

A two putt gave Dufner a cruel double-bogey and dropped him to 3-over for the tournament.

Some players managed to tame the feared course at times, with Bubba Watson rolling in this expertly-judged monster putt on the 10th hole.