79TH CALIFORNIA AMATEUR CHAMPIONSHIP : Wi Leaves Veteran in the Cold : Golf: Teen-age longshot from Thousand Oaks wins title, 3 and 2, as a former champion wilts before his steady play.

PEBBLE BEACH —  A cold fog swept the Pebble Beach Golf Links early Friday, and golfers shivered inside their earth-tone sweaters and jackets.

Only two golfers were hot.

One was about 65 years old. He had just paid $175 in greens fees for the right to play 18 holes of golf and had promptly launched his first tee shot about 20 yards, the ball slamming off a nearby building. The man swore loudly at his misfortune but cooled off moments later.

The other golfer who was hot in the chilling mist of the Monterey Peninsula was just 18. His name was Charlie Wi, and he stayed hot all day.

Wi, who graduated from Westlake High just two weeks ago, completed a fairy-tale week by burying 39-year-old former Stanford golf star Gary Vanier of Pleasant Hill to win the 79th California Amateur golf championship, 3 and 2. It was, by all standards, a remarkable accomplishment for a young player who did not even qualify for the event. As the first alternate, he was summoned to play in the prestigious tournament just six days before it began when the NCAA champion, Arizona State’s Phil Mickelson of San Diego, withdrew to attend a collegiate awards dinner in New York.

“I see the names of the guys who have won this thing,” Wi said. “Guys like Johnny Miller, Ken Venturi, Bobby Clampett and Mark O’Meara . . . so many great players, and I just can’t believe my name will go on the same trophy with them. Wow!”

Wi, of Thousand Oaks, had mowed down all comers since the start of match play Wednesday, and he looked to make Vanier, a former winner of the state amateur and a teammate of PGA star Tom Watson at Stanford, just another victim in the 36-hole championship round.

Wi went 1-up with a bang on the fourth hole Friday, dropping a twisting, 45-foot birdie putt. He made the turn at 1-up, stretched his lead to 4-up and settled for a three-hole lead after 18.

Wi boosted his lead to 4-up on the first hole of the afternoon round when Vanier missed a short putt for par, but soon after it appeared the magic that Wi had brought to the tournament had begun to fade. Vanier whipped a 235-yard five-wood into the green at the par-five second hole and carded an eagle with a short putt to cut Wi’s lead to 3-up.

Vanier birdied the fourth and fifth holes to chop Wi’s lead to 1-up. On No. 6, a 518-yard par-five frequented by sea lions, Wi struggled to a bogey, giving Vanier the hole.

After 24 holes the match was even.

“The best thing Charlie did all day was . . . he pretended he was down three holes, not even,” said his caddy, Jeff Rulon, a former teammate of Wi’s on the Westlake golf team. “From then on, he played like he was three holes down. He got more aggressive and stopped laying back.”

And he quickly put Vanier out of the picture.

Wi won the seventh hole, a par-3, with a par after a magnificent, 65-foot shot from a sand trap left him with a short putt. Vanier had bogeyed the hole.

Wi went 2-up on the 10th hole after Vanier’s tee shot found the real Pebble Beach and turned in another superb shot from a bunker, popping the ball lightly from the sand, over a huge lip of the trap and down softly on the green just three feet from the flagstick.

Vanier could not come back.

It was one of nearly a dozen terrific sand shots that Wi hit during the week. Perhaps only Rommel was better in the sand than the South Korea-born Wi was for five days.

Wi went 3-up on the 11th hole when he nearly holed a 140-yard eight-iron shot, settling for a three-foot birdie putt. He made it 4-up by winning the next hole with a par, and Vanier knew his time had run out.

“I made my charge too early,” he said as he walked down the 13th fairway. “I caught him, but I caught him too soon. Now he’s gotten away again.”

Wi lost the 15th hole after he launched perhaps his only poor shot of the day, a drive that sailed out of bounds. As he stood on the 16th tee, the bespectacled young man brought the face of his driver up to within inches of his own face and said to it, “That’s all right. Don’t worry about it. But this time, do a little better.”

The heart-to-heart apparently worked. He bombed a 275-yard drive down the fairway, then hit his second shot to the middle of the green and needed only to two-putt from 22 feet to close out Vanier with two holes remaining.

When the second one fell and Wi had won the match, he clenched a fist and pumped it briskly one time, his first display of emotion all day.

And then, as he walked off the green with the victory, he smiled broadly and said, “I’m going to Disneyland.”

The crowd of about 100 people who had been drawn to the longshot kid all week roared with laughter and then broke into a loud ovation.

“When I came here, I really didn’t believe I could win,” Wi said. “I wanted to make it to match play, that’s all. And I really didn’t believe I could win it until today, and only after the first round today when I had a three-hole lead.”

Wi almost didn’t make it at all. When he failed to qualify--losing the last tournament berth in a playoff at Los Serranos Country Club in Chino in May--he knew someone would have to drop out for him to get a chance. Few do. But last Tuesday, Wi learned that he was in after the withdrawal of Mickelson.

But he was almost out just as quickly. In the first round of stroke play Monday, he struggled to a 75 at Cypress Point, putting himself in danger of missing the cut for match play. But he came back Tuesday with a blistering round of 68 at Monterey Peninsula Country Club and became the No. 3 qualifier entering match play.

“That’s the day Charlie started to play golf,’ said Rulon, his friend and caddy. “We both knew right then that Charlie was in this thing for real. Everything changed after that.”

Wi knocked off two golfers in Wednesday’s opening sessions of match play, and, on Thursday, he ousted first Craig Steinberg of Van Nuys, a talented veteran who had made it to the quarterfinals for the third year in a row, and then 1989 Southern California Golf Assn. amateur champion Paul Stankowski of Oxnard. That set up his showdown with Vanier.

When it was over, Wi, who turned 18 just two months ago, sat in the press room and talked excitedly of his week. A disgruntled Vanier sat for a few moments and listened.

Then Vanier got up, and, for the first time all day, did something that Charlie Wi could not do--he walked into the tavern at Pebble Beach and drank a beer.