Japan’s Yuka Saso leads by one shot following a difficult first round of the US Women’s Open in Philadelphia.

Saso was one of just four players to beat par on Thursday, carding a two under 68 at Lancaster Country Club in Philadelphia.

She leads by one from the trio of 15-year-old amateur Adela Cernousek, Wichanee Meechai and Andrea Lee, while 10 players carded even par rounds of 70.

Among those who struggled was world number one Nelly Korda, whose bid to maintain her incredible run of form unravelled after just three holes.

US Womens Open GolfWorld number one Nelly Korda (Matt Rourke/AP)

Korda was a massive favourite to secure her third major title after winning six of her last seven events.

But having started with a bogey on the 10th, Korda ran up a septuple-bogey 10 on the par-three 12th after hitting three balls into the water.

Korda’s tee shot found the bunker at the back of the green and her second shot was hit too hard, catching the slope and rolling into the water.

From the drop zone Korda found the water twice more before finally hitting her eighth shot on to the green and two-putting from nine feet to slump to eight over par.

Korda’s dominant run this season includes her second major victory in the Chevron Championship, but she admitted in her pre-tournament press conference that she was expecting to face a “beast of a course” this week.

England’s Jodi Ewart Shadoff opened with a two-over-par 72 with Ireland’s Leona Maguire a shot further back.

Lancaster Country Club has been revised and lengthened to a par 70 of 6,583 yards since it last hosted the US Open in 2015.