The first swing of Thursday for Phil Mickelson sent marshals’ arms pointing waywardly, swallows fleeing from tree limbs and Mickelson to the back of the tee box looking forlorn. It wasn’t even 7:35 a.m. Before Tiger Woods, his playing partner, even struck a shot in the 112th U.S. Open, Mickelson began pantomiming his own swing, trying to find something on the course that might better be discovered on the range.

Woods was next off at the Olympic Club’s Lake Course. He pulled out a driver, stepped confidently to the ball, took a controlled lash, and all but bisected the fairway. Mickelson never did find his ball, or his game. Woods’s, though, was right there in front of everyone, worthy of admiration.

“It was impressive,” Mickelson said.

Woods did not lead at the end of the Open’s long first day. Michael Thompson, a typical who-the-heck-is-that U.S. Open front-runner, held the advantage, because he shot a stellar 4-under-par 66 in the morning. But Woods’s presence was inescapable, because his 69 on a tight and tricky layout included only a scant few errant shots and had all the markings of Woods in his prime.

Woods’s score was matched by 45-year-old David Toms, 2010 U.S. Open champ Graeme McDowell, England’s Justin Rose and Californian Nick Watney, who was spurred by a double eagle. None of those names, all with their own accomplishments, resonated around the bay like that of Woods.

“I felt very pleased with every facet of my game today,” Woods said. Rough translation: Watch out.

“That was the old Tiger,” Masters champion Bubba Watson said. “That was beautiful to watch. That’s what we all come to see.”

Among those Woods dusted on Thursday were his playing partners: Mickelson, who hit into as many galleries as fairways en route to 76; and Watson, who looked disinterested at times during a 78. Olympic’s opening six-hole stretch played as difficult as advertised — the 156 players played it in 420 over par — yet Woods navigated that set in 2 under. More than anything, he kept himself from being one of the marquee players who will enter Friday’s second round more concerned with the cut line than the lead.

Rory McIlroy, the defending champ, struggled to a 77 in which he made eight bogeys. Last year, in winning at Congressional, he made three bogeys and a double — for the entire week. Luke Donald, the No. 1 player in the world, didn’t make a birdie en route to an unsightly 79. Lee Westwood, the other member of the group that included the top three in the world rankings, was brilliant by comparison, managing 73.

“The top three in the world and we make three [birdies] between us,” Donald said. “It shows how tough it is.”

How, then, to explain Thompson’s performance?

“Feeling really calm and relaxed,” Thompson said.

Really? He is 27, lives in Birmingham, Ala., was an Eagle Scout and had played in only one previous U.S. Open. Yet he is extraordinarily comfortable here. Five years ago, he advanced to the final of the U.S. Amateur at Olympic, and though he narrowly lost to Colt Knost, he wanted badly to return for this event. He gained entry by placing second in the sectional qualifier at Rockville’s Woodmont Country Club, a 36-hole day that may have been more pressure-packed than Thursday.

“I teed it up that day really wanting to qualify,” Thompson said, “but at the same time really not having a whole lot of confidence in my abilities.”

That changed in between rounds at Woodmont, where Thompson wolfed down a peanut butter and jelly sandwich in hopes of putting behind a morning 74. He responded with a 68 in the afternoon and flew to Olympic to begin practicing last Friday. His opening round included a stretch from Nos. 11 to 15 in which he made five 3s in a row, and a 10-footer for birdie at 18.

“I don’t give up very easily, and I’m proud of that,” Thompson said. “Give Tiger the spotlight. I don’t care.”

So many will oblige. Woods’s first shot stung down the ninth fairway — an odd place to start, but one made necessary because Olympic’s eighth hole comes back to the clubhouse, and the ninth runs away — and it served simply as a preview. Much of the talk prior to the tournament centered around Olympic’s demand on players to shape the ball because that would be the only way to consistently hold the course’s sloping fairways.

The consensus, from those who saw it up close: “He hit every shot shape he was trying to hit,” Watson said. “I didn’t see any bad shot, really.”

Woods hit only three drivers all day, but stung pure hybrids and irons off the tee. With Mickelson and Watson flailing all around him, he made the first of two bogeys at 14 (his sixth hole), but birdied the par-5 17th, missed a slippery four-footer for birdie at 2, then finally got under par with an eight-footer at 4. He buried a 30-footer for birdie at 5 — “a fluke,” he said. A poor approach into a bunker at 6 led to a bogey, but after a tap-in par at his last hole, No. 8, he could scarcely be displeased, even after a grind of a day.

“It does wear on you,” Woods said, “because there’s no let-up.”

He was speaking about the course. It’s possible, though, that is an apt preview for what’s to come over the weekend. Woods, when he plays like this, can wear on opponents, and there is just no let-up.