Many Masters Tournament participants have seen both sides of Augusta National Golf Club.

There is tournament week, with patrons from all over the world lining fairways and circling tee boxes and greens.

Then there is the rest of the time.

Once a player receives an invitation to the Masters, he can play the course whenever it is open.

Many take advantage of the free pass and use it as a scouting trip. It worked for defending champion Trevor Immelman, who credited a weekend trip two weeks before last year's tournament with helping prepare him.

"It definitely helps coming here before the tournament and just cementing in your mind certain lines off tees and the shape of the shots you want to hit off the tees and where you need to lay up to certain pin positions," Immelman said.

It can even help a player win another tournament. On March 10, Phil Mickelson played 27 holes at Augusta National and hit the ball so well he knew he would contend at the WGC-CA Championship that week in Doral, Fla. He went on to win.

Rookies and amateurs tend to make the most pretournament visits. In the months leading up to his Masters debut in 2004 as an amateur, Brandt Snedeker estimates he played the course at least 40 times.

Former champs can play Augusta National any time because they are honorary members of the club. When Mickelson played it March 10, the stands around the course were already up.

"I have played there in the past where the bleachers are not up and it's eerie," he said.

"It does seem weird," Immelman said. "It's fantastic and you get around real quick and the caddies are so helpful. I've even played there when I used a golf cart.

"That's a real inspiration to be able to play it that way," he said. "There is no crowd. You really get to take it all in. It's just you and the golf course."

Said Tim Clark: "Even though all that stuff is right outside the property, it's almost like you're out in the middle of nowhere just having your own round of golf."

Justin Rose says he can still feel the crowd's presence when he plays it before tournament week.

"It's the kind of course you play it with nobody there, and you feel like 50,000 people are there because it's just got so much atmosphere," he said. "It doesn't ever feel dead. You walk down around Amen Corner and it feels as if the trees are watching."

Paul Casey will never forget his first pretournament week visit to the course.

"You stand up there on the balcony (that juts out from the locker room) when it's not Masters Week and it's just a huge piece of property," he said. "You can see all the way down to the seventh and the eighth holes meandering up and probably down to 15 through the trees. Not what I expected."

Bubba Watson played the course when he was a University of Georgia golfer and was surprised by what he saw.

"Between Nos. 9 and 18 it looks like a big field," he said. "When we went out there with nobody out there, we were like, 'This isn't Augusta. What is this?' Because it's wide open."

It all changes when tournament week rolls around.

"There's a sea of people," Casey said. "You go, 'Wow, there's a lot of people out there.' It's a little intimidating."

Snedeker knows the feeling. As an amateur in 2004, he stayed in the Crow's Nest, a dormitory-style lodging on the top floor of the clubhouse.

Snedeker didn't know what to expect from the Monday practice round, the first day of the tournament week that fans are allowed on the course.

"One of the memories I have is walking out at 7:30 in the morning because I had to get something out of my car and there is nobody there but the security guards," Snedeker said. "The gates opened at 8. I go back upstairs, shower and change and come downstairs at 8:45 and there are 30,000 people right outside the clubhouse.

"I'd never seen that many people before. I flipped out," he said. "I thought, 'I don't want to play golf today. I'll stay in here. I really don't want to go out and hurt somebody.' It was a joke. It's definitely something I'll remember for the rest of my life."