Lee Trevino ran from the practice green to the first tee for the second round of the 42nd Masters yesterday. Then, displaying continued confidence and enthusiasm over a course he once hated, the 38-year-old veteran fired a three-under-par 69 for a 36-hole total of 139 and a share of the tournament lead with Rod Funseth.

Funseth, 45, provided a sharp contrast to Trevino. He had the low round yesterday, a 66, but seemed to further his image as a player who enjoys denigrating his ability.

"I was in pretty much the same situation in this tournament last year, at the halfway point," Funseth recalled. "I called my wife, to tell her the good news about my 67. I was tied with (Tom) Watson. Before I could say anything she asked me, 'Did you make the cut?'"

Funseth, rumored recently to be considering retirement from the PGA Tour, is known for not always taking his game too seriously. Once asked why he didn't practice more, he replied, "Did you ever see some of those guys who practice all the time? They have calluses."

But after the latest two rounds at Augusta National, one of goal's most reluctant heroes was tied with the game's Happy Warrior.

The leaders are one stroke ahead of Gene Littler and Hale Irwin, who posted 68 and 67, respectively. Watson, the defending champion, surged into contention with a 68 and was at 141 with Hubert Green and Leonard Thompson.

An eagle and a birdie in the final four holes enabled four-time winner Arnold Palmer to gain a five-way tie for eighth place at 142, while Jack Nicklaus, the five-time Masters king, again was unable to judge the pace of the slower-than-usual greens.

Nicklaus carded a 73 - 145. "Six shots," he reminded, "is not that much behind . . . but Christ, if I knew why I was putting so badly I wouldn't be putting so badly."

John Schlee, the first-round leader with a 68, came unglued early and often yesterday, slipping to a 75 - 143. Then there was Japan's Tsuneyuki Nakajima, who took a 13 on the par-5 13th.

Nicklaus, Gary Player, Ben Hogan and Gene Sarazen are the only men to have captured golf's four major (Grand Slam) tournaments - the Masters, U.S. Open, British Open and PGA. Trevino has an excellent chance to become the fifth.

"I've quit clowning around here for fear of losing my guest badges," the Merry Mexican quipped. "More important, I'm driving so much longer than I ever have. A drive I hit on No. 2 today must have been the longest of my life. The yardage reads 565. I was 176 out, for a six-iron."

Trevino's drive undoubtedly was not 389 yards long. But it was an extraordinary shot, aided by a long downhill roll and by Trevino's soft cutting of a corner on the left side of the fairway.

That six-iron shot caught the lip of a trap, but Trevino blasted out to six feet and sank his first birdie putt of the day. A 14-foot putt on No. 5 and a four-foot curler on No. 9 earned him a share of the lead for the first time. He needed an 18-foot putt for a birdie on No. 17, however, to offset driving problems on No. 10 and regain a tie with Funseth.

"It's my attitude that's as much responsible for what I'm doing here as my drivving," Trevino declared. "I'm not getting mad at myself here, like I used to. I think the back injury has, in a way, helped lead to my longer driving.

"I haahve to do the exercises,, every morning, for about an hour before I come out. It's like a gravity machine, you attach to the door, and you hand upside down, like on a trapeze, and do situps. It's made me more fit, and stronger, even though I still hate those exercises. They're something I'll have to stay with all my life.

"The pain will be worth it, though, if I could get that fourth major championship." Trevino has won two U.S. Opens, two British Opens and one PGA.

Funseth, by comparison, has only two tour victories to his credit, the most recent coming at Los Angeles in 1973.

"I've had wrist problems and pain in my right hand," he said. "I'll admit I've thought of getting off the tour recently, especially when the hand kept me from practicing. Then I taped two fingers on my right hand together, modified my grip, and everything's been better. I guess I had a bad grip before."

Bridie putts of 45 feet on No. 4 and 40 feet on the 11th keyed Funseth's superb performance. He recorded seven bridies and one bogey with a display of shotmaking that would have had Trevino flying like an eagle. But not Funseth.

'If I did win the Masters, they probably wouldn't have a coat (green jacket) to fit me," he said.

Last year, though tied with Watson after 36 holes at 139, Funseth told reporters he "didn't think" he could win. He shot a 74 and 73 the last two rounds.

Did pressure have anything to do with those scores he was asked.

"About 110 perererercent," Funseth replied.

Trevino, Funseth and Littler, who is 47, are members of the Old Guard which is acquitting itself so professionally this week. Veterans such as Palmer, Don January, Miller Barber and Tom Weiskopf also are in the thick of the struggle. Watson and Jerry Pate are the only under-30 players to be under par. In fairness, however, it should be noted that many of the promising young Turks on the tour were kept out of the Massters by the qualifying requirements.

"There's life in the old crowd yet." Trevino said as he headed back to the clubhouse. "And you know, I think the people here are starting to accept me. They were very supportive out there today. They really applauded when I hit some shots. It was a good feeling."

Twenty-two players bettered par yesterday as scoring dropped sharply. The cutoff point for the last two rounds was 149, with Billy Casper (151) the notable dropout.

For the second day in a row, the back nine was the downfall of Lee Elder. The Washington, D.C., pro shot 40 over that stretch for a two-round score of 148.

"Awful" is how Elder described his play over the final seven holes, an adventure that included three-putt bogeys at Nos. 12 and 14 and a double-bogey 5 at 16 when his tee ball hopped into the water. He had a three over-par 75 for the day.

"One under on the front nine and a hundred over on the back," he said with a groan. "A little like yesterday (when he missed three puts inside two feet on the final nine holes). I've never played here when the greens were this slow. You put a firm stroke on the ball and it's five feet by the hole.

"I really don't deserve to make the cut," he said. "This course is eatin my lunch." Then he quickly chnged his mind. "I can make top 24 from where I'm at. That'll get me back here again."