Webb Simpson wasn't having a bad season before Sunday, per se. Even though he'd missed the cut at consecutive events, he had recorded four top-10 finishes and been competitive in other starts.

Of course, before Sunday, his season paled in comparison to his breakthrough year of 2011, when he earned his first two PGA Tour victories and finished runner-up at three more events.

That was all before Simpson managed the biggest win of his young career, a one-stroke victory at the U.S. Open.

Just like a round at Olympic Club can change in an instant, so, too can a career.

Even in a year when multiple players have scored watershed PGA Tour victories -- Hunter Mahan, Bubba Watson, Jason Dufner, Rickie Fowler -- Simpson's win carries quite a bit of cache simply because of how tough an event the U.S. Open is.

His winning score was 1-over par, and just arriving at that figure was tough, not only because of the course layout and conditions, but because of the pressure. Take it from Simpson himself.

"I just gained all the respect for the guys who have won multiple majors, because it's so hard to do," Simpson said. "The level of pressure is so much greater than a regular event."

Simpson admitted that he couldn't even feel his legs for most of the back nine, and "never felt nerves" like he did Sunday. The 26-year-old added that he was glad he didn't play in the final group, because it allowed him to avoid some pressure that Jim Furyk and Graeme McDowell faced.

Ok, so Simpson wasn't staring into the belly of the beast with the iciest, steeliest reserve, but who could blame him? It's the U.S. Open, which has been known to gobble up a player or two throughout the years.

How exactly did Simpson pull it off? He began the day at plus-3 and bogeyed two of his first five holes, so it wasn't a blazing-hot start. But that rough stretch actually didn't bother Simpson too much.

"I didn't think anything of it because I knew I had seven coming up and a few other birdie holes in the back," Simpson said. "I definitely thought about winning and wanted to win, but I was just trying to keep my mind focused on the hole that I was playing and just somehow make pars."

The North Carolina native began his turnaround at the par-4 sixth, one of the toughest holes on a tough course. He followed up his tee shot with a 7-iron that put the ball within five feet of the cup. Simpson said he wasn't trying to hit it close, but the shot gave him a bonus birdie opportunity.

Simpson followed that with two more birdies in a row, then birdied the 10th to reach plus-1.

Back in contention, Simpson faced his toughest test -- staying there. He managed to par out, and was forced to wait as Furyk and McDowell, both former U.S. Open winners, came down the stretch. That was as nerve-wracking as playing for Simpson.

"I did not want to play a playoff. I did not want to play tomorrow, for a lot of reasons," Simpson said. "It's a tough situation. I've never been in that situation on the PGA Tour watching guys coming in and myself having a chance to win."

Luckily for Simpson, both Furyk and McDowell slipped up. Furyk bogeyed 16 and 18 to fall out of the lead, while McDowell was trying to fight back from four front-nine bogeys. He birdied 17 to get within a shot of the leader, but missed a long birdie chance at the last, and at that point the championship was Simpson's.

This U.S. Open was elusive and frustrating and mentally testing for players. As soon as you think you have a grip on it -- poof, it's gone. And that makes it worse than if you never contended at all.

"That taste of honey definitely is worse than if I would have come back today and shot 2-under and finished in the same score I would be, I'd be walking out here with a big smile on my face and a tie for fourth," Furyk said.

Now, he's frustrated and disappointed. And McDowell's frustrated and disappointed.

Just about the only player not frustrated and disappointed now is Simpson, the guy who, before Sunday, couldn't know what it's like to compete for a major title. Or a U.S. Open title, no less.

Well, he battled the course and his nerves, and that ended up being enough Sunday. Now he's a major champion. Now he knows.