Playing conditions at Shinnecock turned ugly on Saturday. The USGA admitted afterwards they made a mistake in rolling the 7th green before that round. Here is a BBC article about this that quotes tournament officials and players:
"US Open officials have admitted the treacherous short seventh was becoming unplayable and will sprinkle the green with water between each group.
Sun and a stiffening breeze made the greens slick on Saturday, and the par three had become a lottery with drives and putts racing off the green.
The USGA admitted it had made a mistake in rolling the green before the play.
And early in the fourth round they conceded defeat and authorised a light watering to make the hole fairer.
Only one birdie was achieved on the seventh in the third round, and of the last 22 players in the field just three were on the green after their tee shots.
One of those was co-leader Shigeki Maruyama, who then putted off the green.
Despite measures designed to address the problem, the antics continued early in Sunday's final round.
American Kevin Stadler missed a two-foot par putt which rolled 60ft off the green. He and playing partner JJ Henry both took triple-bogey sixes, as did Cliff Kresge behind them.
After Billy Mayfair received a huge roar for a bogey, it was decided that play should be halted for 20 minutes and greenkeeping staff called to water the putting surface.
Walter Driver, the chairman of the championship committee, admitted that officials had been wrong to roll the green before Saturday's third round.
"The change in the wind had a great deal to do with it," said Driver.
"The green is very firm and we had given instruction to stop rolling the green as of Tuesday and I found out today, after the round, that for some reason, a different person on the greens staff had rolled the green this morning despite the orders we had given."
First-round co-leader Jay Haas said on Saturday: "That hole is in the top 10 of all-time difficult ones, and that's out of a lot holes."
England's Lee Westwood added: "If it's an exam paper they're asking you a question that there's no answer to.
"It's playing downwind and the flag's cut on a downslope."
Two-time US Open winner Ernie Els said the Shinnecock Hills course was "as hard as it gets" in the third round.
" I am a little disappointed at what the USGA did to the golf course "
Jeff Maggert
"It's borderline fair," said Els. "That's as tough as the US Open gets, right there. The greens were incredibly tough to play on."
Spain's Sergio Garcia added: "It's right on the limit. If it blows and the pins are tough we'll still be putting on Sunday night."
American Jeff Maggert, who slumped to a four-over 74 for one under overall, said: "You are kind of at the mercy of the bounce.
"I am a little disappointed at what the USGA did to the golf course. It takes a little bit of the skill out of what we are trying to do."
But Masters champion Phil Mickelson insisted he was relishing the testing conditions as he went in search of a second major title.
"I'm really enjoying this. I'm enjoying the set-up. I think the short game is going to play a huge factor in tomorrow's winner," he said.
"What we will have is guys outlasting each other, who can make the most pars before somebody bogeys. That's a fun way to play."