Lee Buck Trevino does his best work in crowds. A usually brooding and weathered face is suddenly enlivened by a switch-on smile, perhaps because among others he can forget that he has been twice married, once struck by lightning and had a childhood so poor "that when the neighbors threw my dog a bone, he had to call for a fair catch."

The double life of Lee Trevino is now in its 46th year and shows no sign of calming. He trails leader Hubert Green by three shots at the PGA Championship at Cherry Hills Country Club, a tournament he won just a year ago to collect his sixth major title.

"At my age, a major is like finding a diamond in a coal mine," Trevino said. "I didn't think I could play this well anymore, especially in a major championship."

How Trevino continues to produce some of the best golf in the world in a career littered with glory and disaster is a puzzle only a little less confusing than his persona. Supermex has long been one of the most entertaining characters on the PGA Tour, and his one-liners have been well chronicled, as has his curious double nature.

Trevino also is known as an enigmatic recluse on the tour, who rarely appears in public off the course. His delightful, quotable nature is equaled only by his reluctance to be interviewed at length. He has a little-known morose side that makes him one of the most intriguing modern champions.

"I would say he's probably the most complex superstar in sports," said Steve Rankin, director of communications for the PGA Tour. "Very few people know what makes him tick. He's very good at dealing with situations the way he wants to. He walks into a room with a preconceived notion of how he's going to work it, and that's what he does. I don't think there are too many people who know him well."

Trevino's careful calculation is perhaps most responsible for his longevity. He has 28 victories, and the Masters is the only major that has escaped him. Coupled with his back-to-back British Open victories, in 1971 and 1972, a second straight PGA victory here would give him a "double-double" and vault him into a special group that not even the most revered modern players of the game have entered.

There was Lawson Little, winner of the U.S. and British Amateur championships in 1934 and 1935, who became the first bonus baby of golf when Spalding offered him $10,000 to turn professional. Bobby Jones won the 1929 and 1930 U.S. Opens, and the 1926 and 1927 British Opens. Walter Hagen won the 1928 and 1929 British Opens, and PGA titles in 1924, 1925, 1926 and 1927.

While Trevino, like Jack Nicklaus, has not won a PGA event this year, he won the British Masters, tied for 10th at the Masters in Augusta and has been named captain of the Ryder Cup team. He was 45 when he won the PGA last year at Shoal Creek in Birmingham, Ala. The oldest player to win a major was Julius Boros, who took the PGA in 1968 at 48.

After a certain number of majors, most of the aging champions start to develop other interests. Some become course designers -- Nicklaus has become one of the most respected in the country. Corporate deals and clinics are parlayed into earnings that surpass prize money. Guest appearances and media requests take away from practice time, and suddenly golf is a complicated game.

"It takes a lot of concentration when you're coming up and laying the foundation," Trevino said. "In 1967 when I was out here pounding golf balls, no one wanted to interview me. Then we got so good, and it just kept ballooning. When you're on top you have to answer all these questions, and your game goes down. I think Nicklaus quit for a couple of years just to see if he could come back. When you're young you don't do other things. When you get older, you do, and it takes away from your game."

Trevino seemed to be going in that direction until last year's PGA victory, which came after a three-year dry spell. His previous victory had come in 1981, in the Tournament of Champions. He had chronic back problems, and some believed his flagging game was a result of being struck by lightning in the Western Open in 1975. In 1976, he underwent surgery for a herniated disk.

But last year's victory at Shoal Creek was perhaps a vintage Trevino tournament. He was one stroke out of the lead on the first day, tied with Gary Player after the second, in the lead by a stroke after the third round and finally won by four over Lanny Wadkins and Player.

"He's a street fighter," said Dave Marr, the 1965 PGA champion and ABC golf analyst, who then marked the width of his chest. "He's got a heart this big. He's been broke and rich, and broke again. He's had a lot of peaks and valleys. You'd be surprised how much easier it is to win a major championship when you're broke."

Trevino's middle-aged surge is more impressive in light of the fact that the PGA Tour has become decidedly more difficult. Two years ago the exemption rules were changed to allow players to qualify more easily for tournaments: instead of making a cut to make it to the next tournament, one simply has to remain in the top 125 on the money list. Consequently, younger players and nonwinners are under less pressure. Rather than just trying to make the cut, they are attacking the courses, shooting at the pins for lower scores.

Formerly, an established champion only had to beat the other established champions. Now there are 140 players who can go on a streak at any time, which is one explanation for the curious state of the tour this year. While Nicklaus, Trevino and Tom Watson have all gone winless, there have been eight first-time winners and 12 playoffs, an indication of growing parity.

"When I first came on tour in 1967, you had to beat 10 guys," Trevino said. "Now you have to beat 60. The fear factor is gone."

Perhaps. But not the ability. While Trevino doesn't have the awesome pure talent of a Seve Ballesteros, who can turn a driver upside down, swing left handed and send the ball 220 yards, Trevino is an original. He is accurate off the tee, only fair with his long irons. But he is a wizard with the short irons and putter, and went until the sixth hole in the third round here before he three-putted. Unplayable shots become playable. If there is no such stroke, Trevino simply "invents it," according to Marr.

"It's like watching someone play piano," Marr said. "He can make a wedge dance in the air."

Trevino's shotmaking never was more evident than at the British Open at Muirfield in 1972, when he won his second straight title. The treeless Scottish course was the setting for what is generally acknowledged as one of the most thrilling championships ever: Trevino and Englishman Tony Jacklin were tied for the lead and Nicklaus lurked six strokes back with 18 holes to play.

Nicklaus, playing a hole in front of Trevino and Jacklin, began to birdie. The final twosome was shocked by the constant roars that came from the course ahead and realized that Nicklaus had played the first 10 holes in six-under par to tie them for the lead. It suddenly became apparent that Nicklaus, who already had won the Masters and the U.S. Open, could win the third leg of the Grand Slam.

Trevino and Jacklin had bogeyed twice and started down the ninth fairway when they were amazed by another shattering roar that drifted across the course. Nicklaus had birdied the 11th hole to take a two-stroke lead.

Trevino stopped and turned to Jacklin. "He might catch one of us," he recalled saying. "But he can't catch both of us."

Several minutes later, Nicklaus heard the roars from behind him for the first time. Trevino and Jacklin had both eagled the hole to put themselves back in a three-way tie. Nicklaus bogeyed 15, and Trevino, naturally, went on to chip into the hole to birdie the 17th and win.

"I'll tell you why he is so hard to beat when he's ahead," Watson said. "Because I think he is one of the best ever to play the game."