NORTH PLAINS, Ore. — Mhairi McKay turned in a surprising performance Thursday with five straight birdies and a 5-under 66, giving her a three-stroke lead to match the largest 18-hole margin in the U.S. Women's Open.

Even more stunning were the players behind her.

Hey, these kids can play.

In a U.S. Women's Open dominated by talk about teenagers, 15-year-old Morgan Pressel played bogey-free golf on a wicked Witch Hollow course at Pumpkin Ridge until a double bogey on the final hole dropped her to 1-under 70.

She was tied with 17-year-old Aree Song, whose 70 matched the best score of the early starters, with 18-year-old Irene Cho another stroke behind.

Michelle Wie, at 13 perhaps the most heralded of the teenagers, blasted drives over 300 yards and finished with a birdie on the tough ninth hole for a 73.

The big Hawaiian played in the final group of the first LPGA major, the Nabisco Championship, and the others look like they want a piece of the action.

"Great, great talent," McKay said of the 14 teenagers at Pumpkin Ridge, which the USGA believes to be a record. "They're probably looking at Michelle and gaining confidence."

Now, they could look all around Pumpkin Ridge.

Of the 14 teens, 10 shot no worse than 76 — the average score on an otherwise punishing afternoon at Pumpkin Ridge.

Defending champion Juli Inkster, a 43-year-old with a daughter the same age as Wie and Sydney Burlison (81), birdied the final hole for a 69. She was tied with Donna Andrews.

McKay, Inkster and Andrews were the only players to break 70, while there were 20 rounds in the 80s. The worst belonged to Kathryn Cusick, who had a 93.

Annika Sorenstam, going after her second straight major, opened with a 72.

Of the eight players who broke par, two were teenagers.

"I'm playing well," Pressel said with a shrug. "I'm not going to say I expected it, but I'm not surprised by it."

McKay has been working hard on her swing, and it came together at an opportune time. She made four straight birdies with wedges in her hand, then finished off her string with a 5-iron into 15 feet at No. 16.

The three-stroke lead was the largest after the first round of the U.S. Women's Open since Helen Alfredsson in 1994.

McKay stumbled down the stretch, hitting a poor drive on the 16th that led to bogey, and missing the green on the 17th for another bogey.

But she ended in style on the 502-yard 18th, clearing the hazard with her second shot and leaving herself a delicate pitch from the left rough. The ball came out high and soft, landed on the front of the green and grazed the left lip before stopping 2 feet away.

After tapping in for her eighth birdie of the round, McKay turned to the crowd on both sides, then tossed her ball into the grandstand.

It was only the second time she had shot in the 60s at a Women's Open, but McKay knows better than to get overly excited.

"It's Thursday," she said, holding out her arms to quell the optimism. "You can't get too far ahead of yourself."

No one can ever be too far ahead of Sorenstam, who scrambled out of a tough start with three straight birdies. The best player in women's golf closed on a disappointing note, three-putting from 30 feet for bogey to finish 1 over par.

That left her six shots out of the lead, and behind three teenagers.

TIGER LEADS WESTERN: Here's one way to quiet all that talk about a slump.

Tiger Woods tied a course and tournament record with a 9-under 63 Thursday, taking a 2-stroke lead at the 100th Western Open. It was his lowest round of the year, and his best since he shot a 63 in the final round of the Disney Golf Classic last October.

Woods is the 13th player to shoot 63 at the Western — a tournament he's won twice — and the first since 2000.

Talk that Woods was in slump was building even before the U.S. Open. After winning three of his first four events this year, he wasn't a factor at the Masters and wasn't in contention at his next two tournaments.

But it was a disappointing weekend at the Open, also played in the Chicago area, that really got the chatter going. He struggled with a balky putter all week, and never made the charge fans expected. For the first time in four years, he didn't own a title from one of the four major championships.

Woods insisted Wednesday that his game was fine — and he more than backed that up Thursday. He hit 10 of 14 fairways, and 15 of 18 greens. And that putter that's given him so much trouble? He needed only 27 putts for the day.

He's two strokes ahead of David Toms, who shot a 7-under 65, while defending champion Jerry Kelly had a 66.