Tom Watson stood on the 18th tee at the Merion Golf Club today doing what he hates most: waiting.

Golf's best player is also one of its fastest, and Watson had spent much of today's final practice round before Thursday's start of the 81st U.S. Open here trying not to let the slow play get to him.

He bounced a golf ball off the face of his driver, trying to conceal his impatience. He shook his head in disgust. Later, when asked how he played, he shrugged. "How can you play seriously when you wait 10 minutes on every tee?"

Tom Watson is a man who does not like to wait. He has waited a long time -- for him -- to win a U.S. Open. When he tees it up at 2:05 p.m. Thursday with playing partners Bruce Lietzke and Isao Aoki, it will be his 10th try at the Open title.

"I want very badly to win the Open," Watson said today. "It's certainly my No. 1 goal right now. But I don't have a fetish or a phobia about it. I have to just let it happen. I can't force it to."

For the average mortal, Watson's record in the Open is good. He has finished among the top 10 in six of the last seven years, including a tie for third in 1980.

But Watson is not average. He has been the leading money winner and player of the year on tour four straight years. He has won three British Opens and two Masters and could have won this tournament at the age of 24 if he had shot 73 on the final day. He shot 79.

For Watson, winning the Open is adding another piece to a puzzle he began putting together with remarkable precision in 1977. Since then, he has won 25 tournaments. No other player has won more than nine. During Jack Nicklaus' peak years (1971-1975), he won 23 tournaments, five of them majors, going into the '75 Open. He had added two titles, including a sixth major, by the end of that year.

In a comparable period Watson has won two more tournaments and four majors.

In other words, his record for 4 1/2 years is comparable to that of the man considered the greatest player of all time during his peak period as a player.

But still there is no U.S. Open trophy, a blemish that is unmistakable even amidst the glitter of the other achievements. It is a piece Watson must add to the puzzle, a job still to be completed.

"I don't think Tom's obsessed with winning here," said John Cook, one of the young players given a chance here. "But I think he knows that if he wants to be one of the game's true greats , he has to win this tournament."

Watson's goal in life is simple: to be the best who has ever played. At 31, with five major titles, he is a long way behind Jack Nicklaus, who has 19. Nicklaus has won this tournament four times

"No, it doesn't get harder every year," Watson said in answer to a question. "I know what I have to do to win here. I have a game plan for the course. I wish I felt a little more positive about my game, about my swing right now.

"I'm still searching for that secret to the swing."

Many of the players think this will be Watson's year, that Merion is the kind of course he can win on because it does not emphasize his weakest point, driving, and it does emphasize his strongest, putting.

"It's got to help Tom that he's only going to have to drive the ball four or five times each round," Ben Crenshaw said. "He's very good with the three-wood or the one- or the two-iron. Once he gets the ball in play, he'll be tough around the greens. He always is."

Watson agrees that the shortness of the course, 6,544 yards, will enable him to keep his driver where it is safest -- in his bag. "My driver is probably the reason I've never won the Open," he said. "So it's safe to say not using it much will probably help me."

But Watson thinks there are at least 20 players capable of winning here: Nicklaus, who lost a playoff to Lee Trevino here 10 years ago; Trevino, who shot 65 in a practice round Tuesday; Ben Crenshaw, also a superb putter; Tom Kite, consistent as they come; Cook and John Mahaffey, not long hitters, but accurate; Aoki, last year's runner-up, who next to Watson, may be the world's best putter, and Gary Player, who has won nine majors.

"The list goes on and on," he said, smiling the Watson grin that both disarms and intimidates. "I'd just like to go out and get a good start tomorrow. I haven't done that in the past, and it's hurt me."

In fact, Watson has broken 70 in an Open first round just once, in 1975, when he opened with 67-68 before fading the last two days. Last year he was eight shots behind Nicklaus after one round. He outshot Nicklaus by four shots the last three days.

Watson wants this title if only so he doesn't have to answer any more questions about not having won it. He is a man whose goals are clear, who knows where he wants to be and when.

Sometimes, the necessary intrusions get in the way, such as signing autographs and talking to the press.

His answers to questions are always polite, smooth and articulate. But he can turn almost any personal question into an analysis of a hole, a green or his swing. He smiles when he hears people talk about the Open being his "Holy Grail," but clearly it is something his few close friends on the tour don't even like to talk about for fear of saying the wrong thing.

"Of course he wants to win it," said Lanny Wadkins. "Tom wants to win everything he can."

That is an oversimplification. When Watson plays in the Greater Greensboro Open he wants to win; when he plays the Open, he burns to win. "It's a lot harder to win the first one than to win the fifth," Nicklaus said.

"You can look at him this week and see he can't wait for Thursday," Cook said. "He's had a week off, he's playing well, this is what he's been waiting for. He wants this one bad."

And what, Watson was asked, will be running through his mind when he steps onto the first tee in what promises to be torrid heat on Thursday?

"I'll be thinking about hitting a good drive, like on any hole," he said.

Then: "Actually, I'll be thinking about shooting 62 and then following it with 65-70-70 so I win the tournament by 15 shots."

The line drew a lot of laughter. More important, though, it gave Watson a chance to end the press conference. He wanted to get moving and he didn't want to wait.