SOUTHAMPTON, N.Y. – Ha-Neul Kim of South Korea upstaged her friend, Inbee Park, to take the first-round lead Thursday at her first U.S. Women’s Open.

Kim shot a bogey-free 6-under 66 to lead Park by a stroke. The top-ranked Park is trying to make history by winning the first three majors of the year.

“I’m enjoying myself,” Kim said through a translator. “I’m just happy to be here and to be playing in this big event. I’m not really thinking about winning or results but enjoying the moment.”

A member of the KLPGA Tour, Kim is a seven-time winner in South Korea. She kept giving herself short birdie putts and making them.

Kim birdied her second-to-last hole with daylight waning to claim the lead after Park held it for most of the day with her 67 in the morning session.

PGA: Roberto Castro led the way with a 5-under 66 in the first round of the AT&T National at Congressional in Betheda, Md. He made three straight birdies late in his round with a 20-foot putt, a perfect 3-wood into a par 5 and a chip-in.

“There’s not a lot of birdies out there,” Castro said.

“There’s not many good breaks or bad breaks to be had out there. If you drive it in the rough, you drove it in the rough. If you hit it in the fairway, you can go from there.”

Billy Horschel, who tied for fourth in the U.S. Open two weeks ago, began his day with a 50-foot birdie putt, added a pair of birdies over the next three holes and then hung on for a 68. That was the best score among the early starters. Bud Cauley and Graham DeLaet each had a 68 in the afternoon.

EUROPEAN: Saying he’s “feeling a bit lost” in a difficult year, Rory McIlroy shot a 2-over 74 in the Irish Open to fall eight strokes behind the first-round leader, Oscar Floren.

The second-ranked McIlroy, from Northern Ireland, had four bogeys and two birdies in wet and overcast conditions at Maynooth, Ireland, on the outskirts of Dublin. McIlroy hit only 5 of 14 fairways and took 34 putts.

“At the moment no aspects of my game are strong and I’m just feeling a bit lost,” he said. “It feels good on the range and I can hit all the shots, but when I get out on the course it really does not seem to be there.”

CHAMPIONS: John Huston shot a 5-under 65 to take the first-round lead in the Senior Players Championship at Pittsburgh.

Huston started on No. 10 and was even par halfway through his round before making a big move on the front nine .

Fred Couples, Duffy Waldorf, Fred Funk and Russ Cochran were a stroke back in the third major on the Champions Tour schedule. Tom Pernice Jr. had three straight birdies to start his round and led a group of players at 67.

NOTES

THE LPGA Championship is staying in Pittsford, N.Y., but will be switching dates and courses next year.

The major tournament will be held the week of Aug. 11 and played at the Monroe Golf Club. That’s a change from previous years when nearby Locust Hill Country Club hosted the event in mid-June.

THE WINNER of next month’s British Open at Muirfield in Scotland will pocket $1.4 million, up $68,600 from last year.

The Royal & Ancient, which organizes the major tournament, said the total prize money will be $8 million, an increase of $380,000 from 2012.