The Associated Press

Annika Sorenstam found herself battling a difficult Pumpkin Ridge course Thursday. (Associated Press photo) | ZOOM |

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.

"Great, great talent," McKay said of the 14 teenagers at Pumpkin Ridge, which the USGA believes to be a record.

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 birdied the final hole for a 69. She was tied with Donna Andrews, while Annika Sorenstam had to scramble for a 72.

Inkster said experience helps only if shots are finding the fairways and greens.

"I could have the most experience in the world, but if I'm not hitting the shots, it's not going to pay off," she said.

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's 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.

Sorenstam 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.

"I'm tired," Sorenstam said. "I was thinking on every shot."

One constant about the U.S. Women's Open is that trouble is waiting in the bunkers, water hazards and anytime someone winds up on the wrong side of the hole.

Laura Diaz was at 3 under and leading with three holes left when her tee shot landed next to the lip of a bunker, forcing her to chip out. A poor 3-wood continued the spiral toward double bogey, and a bogey on the ninth left her with a 71.

"The U.S. Open is the most roller-coaster golf that you probably will ever see," she said.