Michelle Wie breathed a huge sign of relief as she reflected on having finally lived up to the burden of expectation by winning a first major title with a two-stroke victory in the US Women's Open.

More than a decade after having become famous for almost making the cut against the men in a PGA Tour event, the 24-year-old from Hawaii was on an emotional high after having won the biggest prize in women's golf.

"I'm just unbelievably happy," she said after shooting an even-par 70 to hold off her fellow American and world No.1 Stacy Lewis (66) over the taxing Pinehurst No.2 course. "I'm so honoured to have my name on the trophy, so grateful for everything."

Wie seemed poised to win in style until she double-bogeyed the 16th hole after almost losing her ball in a thick clump of wire grass after a poor second shot. It took some two minutes to locate the ball and she subsequently chose to take a penalty stroke, eventually sinking a five-foot putt to avoid dropping three shots. "I definitely gave myself a heart attack when I couldn't find that ball," she said. "I was stressing out, for sure. All you can do at that point is laugh. I joked with my caddie that we really like to make things difficult for ourselves."

The pressure was immense when Wie stepped on to the par-3 17th tee with a tenuous one-shot lead. She responded magnificently, sinking an 18-foot birdie that she described as "the best putt of my life".

After she secured par on the last win, she lifted her right hand to her mouth as if she could not believe what she had achieved, before breaking out in a huge smile. Wie, who previously had twice led into the final round at the US Women's Open, won $720,000, small change for a woman who has made millions in endorsements.