SAN DIEGO — Not long ago, the question wasn't so much if Tiger Woods could win the Grand Slam as whether he could win every tournament he entered this year.

With the U.S. Open beginning today, though, the thought of Woods going undefeated has been left behind.

And the only player with a chance at the Grand Slam?

That's Trevor Immelman.

So while Woods, Phil Mickelson and Adam Scott, the top three players in golf, tee off in a rare glamour threesome at Torrey Pines, Immelman will be in a much quieter pairing later in the day: himself, Zach Johnson and Mike Weir — the last three players to win the Masters not named Woods or Mickelson.

"A fantastic pairing," Immelman said of the Woods-Mickelson-Scott threesome. "I'll probably be watching some of it before I tee off. But there's a whole host of players that have a great chance on this course."

Immelman is one of them. Not only does he have the confidence of Augusta behind him, he also has the memory of winning one of his first big tournaments, the U.S. Amateur Public Links, right here at Torrey Pines in 1998.

If only the Torrey Pines of 10 years ago was the same that the players will see this week.

"Make no mistake, this is a seriously difficult golf course," Immelman said. "But it's fairly set up, from what I've seen the last couple of days."

It is long — at 7,643 yards, the longest course in major championship history.

But the USGA has given itself some flexibility, too, having placed multiple tee boxes on a number of holes to add options if the wind is blowing or the rough gets out of control or the greens become too much.

Or all three.

USGA officials are at least talking like they're trying to change this year.

"We wanted to keep it the hardest championship in golf," said Mike Davis, the senior director of rules and competition. "But we wanted to introduce risk and reward, and widen the scoring opportunities. You'll have a chance to make birdies, but if you don't execute the shot, you can make bogeys or worse. We just want to get them thinking more."

To improve chances for a fantastic finish, the likes of which have been missing from U.S. Opens of the recent past, Davis persuaded his USGA compatriots not to turn the 18th hole into a long par-4.

Instead, it remains a par-5, reachable at 573 yards, but with a pond guarding the left half of the green and no grass to hold balls that land in front and spin backward.

Someone in desperation mode come Sunday might try to go for that green.

"It really makes you think," Immelman said. "You've got to decide if you're going to for it or lay up. If you hit it over the back and get a bad lie, you can chip it in the water easily. It's going to be a fantastic finishing hole."

Despite the injury, Woods was listed as a 5-2 favorite. Mickelson was next at 7-1. Well down the list was Immelman, at 33-1, even though he's coming off a second-place finish last week at the St. Jude Championship, where he lost in a playoff to Justin Leonard.

A longshot indeed. But he's been in this spot before.

"The thing you take with you is that you've done it before," Immelman said. "That's always comforting, to know you've won on the biggest stage."