Forget for a moment that Tom Watson, who has won more major titles the last three years than any other golfer, and Peter Oosterhuis, who hasn't won even a minor tournament since 1974, popped up yesterday as the third-round leaders, by a stroke, of a British Open championship that still could be won by a list of guys as long as a driver.

To appreciate fully a day when so many players - reknowned and obscure, young and venerable - were in serious contention that the leader board looked like the lineup for "War and Peace," consider these things. They all happened on the bumpy fairways, frightful bunkers and enormous greens of the Old Course at St. Andrews:

Watson, doing well despite feeling "disorganized," shanked a sand wedge at the 17th, but got a lucky carom onto the green and saved the bogey. He was satisfied with that, because he called this notorious "Road Hole" "the toughest par-4 I've ever seen."

Ben Crenshaw, the best putter on the professional tour, three-putted back-to-back holes from 30 feet, then made a birdie and 13 consecutive pars to tie Jack Nicklaus and a couple of guys named Isao Aoki and Simon Owen. They are at 212, Watson and Oosterhuis at 211.

Spaniard Severiano Ballesteros, the swashbuckling 21-year-old 'Arnold Palmer of Europe," plummeted from the lead shared with Crenshaw and Aoki to a five-way tie for 13th by shooting 40 on the back nine.

The real Arnold Palmer also took 40 strokes after the turn, driving out of bounds and making a triple-bogey 7 at the tortuous "Road Hole" for the second consecutive day. He plunged, as flamboyantly as Ballesteros, from one to six strokes off the lead.

Australian writer-golfer Peter Thomson, who won five British Opens between 1954 and 1965, started with a double bogey, birdied four of eight downwind holes, then had two more bogeys coming back into the breeze to finish the day three strokes behind the leaders. he could not file a story back to Australia, however, because of a telecommunications strike in Scotland.

And there was Tsuneyuki Nakajima, one of three Japanese players in the hunt, who was overjoyed at reaching the 17th green in two shots, leaving himself 60 feet away from the birdie that would have put him five under par.

He promptly putted past the hole and into a bunker, where he stayed for four exasperating swings. On in two, he took a 9, and probably earned a permanent place in St. Andrews lore as the windmill of the "Road Hole."

"Now," one colleague said wryly, "they may have to change the name of the 'Road Bunker' to 'the Sands of Nakajima.'"

It was, in short, a typical British Open day, one that truly could be absorbed only by that mythological creature with 10 heads, and only then if a couple of the heads were mounted on very long necks for maneuver-ability.

The sun shone brilliantly. The wind picked up, though it still was not as troublesome as usual at St. Andrews. After 40 intriguing twosome had finished doing interesting things, the 107th Open remained, as Watson put it, "anybody's ball game."

Last year, after 54 holes, the third leg of the modern Grand Slam had come down to a match play contest: Watson vs. Nicklaus. Everyone else was merely along for the ride as they dueled head to head the last round at Turnberry, on Scotland's west coast, Watson shooting a 65 to trump Nicklaus' 66.

Most experts expect the some two masters to break open today's final round. But as Nicklaus said yesterday, "There are a whole bunch of other guys around this time."

Watson and Oosterhuis are five under par after three trips around the hazardous Old Course, which got tougher as the breeze and sun dried out the greens, making them hard and fast.

Englishman Nick Faldo and three Americans - 1973 champion Tom Weiskopf, Tom Kite and John Schroeder - are at 213, whle Thompson and Australian Bob Shearer are at 214.

Ballesteros, Hubert Green, Ray Floyd, Guy Hunt, Dale Hayes and Bob Bynam are at 215.

Add them up, and you will find 18 players within four shots of the lead.

Watson, who won the 1975 British Open at Carnoustie and last year's at Turnberry, bounced over the creek called Swilcan's Burn on the first hole and got away with poor sand wedge shots at the third, sixth and 10th holes.

A good drive and a two-iron nailed to within 40 feet of the pin got him a birdie on the 564-yard fifth. "Until then, I didn't feel like I knew what I was doing," he said. "But that got me going."

The 50-foot putt he sank on the eighth green got him going a little more.

Birdie putts of 20 feet on the 12th and 13th holes thrust Watson into sole possession of the lead, but the greatest good fortune of his charmed round came at the 17th.

He tried to open up the face of his sand wedge to punch over the "Road Bunker" and stop the ball on a treacherously tight green.

Instead he caught the ball with the neck of his club and shanked a line drive into the top of the bunker. The ball popped into the air and ropped onto the green, 25 feet from the hole. Two putts got him a bogey 5 where he might have found Nakajima-Style disaster.

Osterhius, 30, born in London but now living in California, played a solid round, making birdies at Nos. 4, 5 and 11. The 6-foot-5 long hitter kept the ball within the fairways, and came out of bunkers well, an art that has often escaped him.

"Four years ago, I was thought of on top of things over here and there was a lot of pressure on me," he said.

"But the way I've played since then, no one expects much of me anymore. Of course I'd love to win the British Open, but at this stage I'd be thrilled to win any tournament at all."

Crenshaw left a downhill 30-foot putt two feet short on the third hole and missed the second putt, an unpardonable sin for him.

On the next hole, he left a 30-footer five feet short and missed again. But on the fifth, he creamed a drive and a three-wood and got down in two putts from 60 feet past the hole.

"That was very important in turning around my round," said the 26-year-old Texan. "I scrambled on the back nine and made some good putts. I didn't think I played my best golf; I hope I was saving it for Saturday.

"If the weather stays as it has been, it's going to take aggressive golf to win. But nobody tears up this course. You have to take liberties when they present themselves and play cautiously when the situation dictates. You can't go firing at every flag. There is no way."

Aoki, 35, was the first-day leader and he has surprised everyone with his staying power. Yesterday he holed an 18-foot putt on the tricky 18th green after bogeying the 17th.

"I came here to win, not just to participate" he said through an interpreter.

The translator reckoned that Aoki was costing millions of his countrymen a good night's sleep.

"Today's round was on live on Japanese television," he said. "I think everybody is watching even though it is 2:30 in the morning."

"It's a horse race now" said Watson. "You don't want to let anyone gets too far out in front. This is too difficult a course for anyone to play without thinking. How aggressive you can be depends on what everyone else is doing, and we won't know that until we're out there."