SAN FRANCISCO — Louis Oosthuizen's drive drifted deep into the right rough. He laid up short of the green and stood in awe while measuring up his third shot.

Only 240 yards remained.

"If anybody is on the green in two this week, that's something special," 2010 British Open champion Oosthuizen said of the longest hole in U.S. Open history, the remodeled par-5, 670-yard 16th at The Olympic Club.

If length weren't enough, the sharp dogleg left feels like a constant U-turn and the fairway narrows past 300 yards. The flag is often blind until the third shot, and balls that miss long or left will bounce farther away because of grass mowed razor-thin beyond the tiny green.

"The reason we did that is we really felt that would make it a true three-shotter," said USGA executive director Mike Davis, who oversees course layout for the event that starts Thursday.

"The wonderful thing about that hole is that from the back, if you miss any one of your shots, it's awful hard to catch up."

Players are learning that lesson in practice rounds.

Oosthuizen could not remember pulling out a 5-wood for his third shot before, hacking out of so much rough — "the thickest on the entire course," he said — on the previous swing he had little choice.

Staring at the elevated green, he couldn't imagine even the field's longest hitters — Dustin Johnson and Bubba Watson among them — going for the flag in two.

The previous longest U.S. Open hole was the 667-yard 12th at Oakmont in Pennsylvania in 2007.

Note

• He is about to become the youngest player since World War II in the U.S. Open, but Andy Zhang doesn't look like a 14-year-old from a distance.

Zhang, who came to the United States from China when he was 10, is 6 feet tall and weighs 174 pounds. He has a fluid swing that can propel the ball a consistent 280 yards off the tee.

But once you get closer, he is truly a 14-year-old. He has a full set of braces on his teeth. He peppers his conversation with words such as "like" and "actually." The one thing he wanted to do the first time he arrived at the course Monday was to go to the practice range and get autographs, especially the signature of Tiger Woods.

Instead, Zhang said, "People are asking me for autographs and I'm like, 'What?' "