PGA Tour pro Jordan Spieth reacts to chipping in from...

PGA Tour pro Jordan Spieth reacts to chipping in from the bunker for a birdie on the 18th hole during the final round of the John Deere Classic golf tournament in Silvis, Ill. (July 14, 2013) Credit: AP

Don't be fooled by the cool under pressure, that stoic look on his face or those amazing results under intense the spotlight. Jordan Spieth really is capable of being impressed enough by the newness to stop right in his tracks.

It happened after the 20-year-old co-leader was leaving the scorers building after his round. He saw his caddie, Mike Grellen, surrounded by more than a dozen reporters, giving an interview. Spieth broke stride, stared and said, "I've got to get a picture of this!"

Even then, he had a wide smile on his face, which means the kid is composed even when he is wowed. "He has always been like that, though, since I met him at the U.S. Junior," Grellen said of the golfer who is tied for the Masters lead with Bubba Watson at 5 under. "He has always had an inner calmness you don't see in a 20-year-old."

You don't see a 20-year-old who has won a PGA Tour event, something Spieth did last summer taking the John Deere Classic in a playoff when he was still 19. The last teenager to pull that off was Ralph Guldahl in 1931.

Nor do you see many golfers who have won the U.S. Junior Championship twice. The only other one to have done it, in fact, was Tiger Woods, whose absence has been the biggest story here this week. But Spieth is gaining on him, importance-wise.

Spieth is the youngest 54-hole co-leader since they started holding the Masters 80 years ago. He also is the only one who can claim a share in the top spot only four years after being cheered by classmates at Jesuit College Preparatory School in Dallas while he was playing in the Byron Nelson Championship (he finished 19th).

The youngster is the only one in the field who keeps referring to former champions as "Mr. Crenshaw," "Mr. Nicklaus" and "Mr. Watson." There are two of the latter in Spieth's vocabulary: Tom, the venerable Hall of Famer, and Bubba, with whom Spieth will be paired in the final twosome today.

The honorific will partly be a sign of respect, Spieth said, and mostly, "just because it will mess with him."

In the midst of all this, it would be easy to say he is the future of American golf. That would be unfair and inaccurate. Spieth is the "now" of American golf. He has as good a chance to win the green jacket Sunday as anyone.

"He's an amazing player," said Matt Kuchar, who is tied for third and who admirably tied for 21st as a 19-year-old amateur here in 1998.

Fred Couples, who is four strokes back and who won the Masters the year before Spieth was born, said, "He can play well anywhere. He hits the ball long and high. For a 20-year-old, he's pretty savvy. Not much bothers him."

Couples captained the U.S. Presidents Cup team last year, on which Spieth was a valuable member. He said, "Tomorrow obviously is going to be a really, really hard day to try and win this, but he's well qualified to do it."

Whenever a young golfer does something outstanding, there is a rush to call him "the next Tiger Woods." Many people fell into that trap when Rory McIlroy won the 2011 U.S. Open at 22. McIlroy might even have been among them, signing a huge deal with Nike -- Woods' equipment company -- a deal that hasn't exactly helped him play well.

Being the first and only Jordan Spieth is plenty. He was mature enough to be conservative when it was wise Saturday. He literally talked to himself at key moments, which didn't faze his caddie. "I taught sixth-graders for 10 years. I'm a very patient person," Grellen said.

"It's all just brand new experiences, playing with house money. I think we're too dumb maybe to know where we're at," the caddie said.

Don't you believe that, either. Spieth knows exactly where he is and he is convinced he belongs there.

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