HAVRE DE GRACE, Md. - This is all so new for Anna Nordqvist, who turned 22 Wednesday. She left college life at Arizona State to embark on the nomadic life of a 2009 LPGA Tour rookie learning on the run.

Now she enters the weekend of the McDonald's LPGA Championship, just her fifth event on the women's tour and her first major as a pro, in the lead.

The former Arizona State star by way of Sweden sank a 36-foot birdie putt on her final hole at Bulle Rock for a 2-under-par round of 70 to take a 1-stroke lead over Nicole Castrale at the halfway mark of the tour's second major of the season.

Not bad so far for a player who considered fellow Swede Annika Sorenstam her role model. Of course, she could start following in the golf footsteps of Sorenstam, who won 72 tournaments including 10 majors, by holding on today and tomorrow to gain the trophy.

"It feels great," she said. "I've had a lot of fun so far. This is my first major as a pro; I played the British Open [as an amateur] in '07 and '08. It's a great experience so far."

Asked if she was ready to win a major, she replied, "I'm here to learn, and we'll see in the next couple of days. I'm just going to try to focus on my game, and if I'm ready, I'm ready."

Castrale played her final 13 holes in 3-under for a 72 and second place at 137, a shot behind. Katherine Hull and Lindsey Wright, Australians and former college teammates at Pepperdine, were at 138.

Hee-Won Han, who, with six career victories, owns four more than everyone else in the top 10 after yesterday's round combined, fired a 69 to head a three-way tie at 139.

Lorena Ochoa, the No. 1 player in the world seeking her third major championship, made a move with a 69 that left her at 3-under 141, 5 shots off the pace. She is working on a streak of five top-10 finishes at the LPGA Championship, including a tie for third last year, 1 shot out of a playoff.

"I gave myself a lot of birdie chances," Ochoa said. "A few putts didn't drop, but I'm happy. When I looked at the scoreboard, it surprised me because it is not easy out there. So I'm happy. I am right where I want to be."

Nineteen-year-old Michelle Wie suffered four bogeys in her round but picked up a birdie down the stretch for a 74 and a 144 total.

On a sunny, muggy day, the first time all week it did not rain, Nordqvist improved her score to 9-under with three birdies in her first eight holes but gave back a pair of shots and fell back into a tie with Castrale. But she edged in front on her last hole, the 413-yard ninth, by hitting a 5-wood approach to the back fringe and draining the putt.

"I was just trying to go out there and have fun and enjoy the day," she said. "I think I had a pretty solid day."

Castrale got off to a rocky start, standing 3-over for her round after five holes following a double bogey at the 12th hole, where she dunked her tee ball into the water, and a bogey at 14. But, aided by the encouragement of her husband and caddie, Craig, she settled down, going without a bogey the rest of the way while carding three birdies.

"After the 14th, I had made only one bad swing," she said. "Craig kept reminding me that other than the one bad swing, I'm still hitting it pretty good. The course was playing tougher, but I figured I could get a couple of more birdies coming in. It was just all about staying patient.

"You know, I didn't quite have it today, but I was able to grind out an even-par round under these conditions, which was good."

Notes. The cut was at 3-over 147. Brittany Lincicome, winner of the Kraft Nabisco Championship in March, was a casualty at 148. . . . Former Montgomery County resident Lisa Strom came in with a 77 and finished her week at 153.

Contact staff writer Joe Juliano at 215-854-4494 or jjuliano@phillynews.com.