OAKMONT, Pa. (AP) — This was no magic trick, just Oakmont.

Steve Stricker was standing next to his bag marking his golf balls before his final practice round Wednesday at the U.S. Open when he dropped one on the green. He watched it trickle around the bag, appear on the other side and hit someone in the foot, a 180-degree turn over an area of 5 feet.

The smile on his face disguised a wince.

Stricker is among the best putters in golf, and even he took a breath on the eve of an Open that will be held on a course reputed to have the fastest greens in the land.

This is his 12th U.S. Open, and he has come to expect narrow fairways, shaggy rough, firm greens, frayed nerves.

“The setup is comparable from the tee until you reach the green,” Stricker said. “But once you hit the green, it’s another game.”

More than its reputation as the toughest course in America, more than the Church Pew bunkers, with or without 5,000 trees, what sets Oakmont apart from other U.S. Open venues is the greens.

Oakmont opened in 1903, and while there have been changes over the years, the greens remain virtually untouched.

“These are the toughest greens we’ll ever play in U.S. Open history, or even any other tournament for that matter,” said Ernie Els, who won at Oakmont in 1994. “With the rough and these greens, this is going to be a very, very tough test.”

But that was before a thunderstorm moved into Pittsburgh and pounded the course with four-tenths of an inch of ran in an hour. USGA officials were hopeful it would not change the course dramatically, but it figures to take some of the fright out of firm and fast conditions.

“It’s not going to be what we planned for,” USGA agronomist Tim Moraghan said. “Things were moving along quite well. We thought we’d have a true, hard test for players on Thursday. The rain has altered this a little bit.”

Moraghan said the rain should not affect the speed on putts, but softer greens would more easily hold shots from the fairway.

Before the storms, it was not surprising to see so much activity on the putting green, an extension of the ninth green at Oakmont. Tiger Woods took the day off, except to hit balls on the range and work on his putting.

“They are by far the most difficult greens I’ve ever played,” Woods said. “I thought Winged Foot was pretty tough. Augusta is pretty tough. But both courses have flat spots. Augusta may have these big, big slopes, but they have these flat shelves that they usually put the pins on. Here, I’m trying to figure where a flat shelf is.”