The latest US Women's Open champion credited her caddie for helping close out her first major title.

South Korean Park Sung-hyun won the 72nd edition of the oldest major in women's golf in New Jersey on Sunday (local time), shooting a five-under 67 in the final round at Trump National Golf Club in Bedminster for a four-round total of 11-under 277. Park, an LPGA rookie, defeated South Korean amateur Choi Hye-jin by two strokes.

Park started the day at six-under, three shots off the lead, held by Feng Shanshan of China, but some clutch plays on the back nine catapulted her to the monumental victory.

She made key birdies at the 15th and the 17th holes to take a two-stroke lead, but it was the beautiful bump-and-run from the back of the green at the 18th that sealed the deal for the 23-year-old.

In a televised interview later, Park credited her veteran caddie, David Jones, for calming down her nerves before the shot at the 18th, which was fraught with some ugly possibilities. Park rolled the ball merely inches from the hole and tapped it in for a closing par.

"My mind went blank, and I became quite nervous over that shot," she said. "But David told me just to relax, because it was the type of shot that I'd been practicing so much. And I executed the shot just the way I'd practiced it. I actually surprised myself with the result."

Park, a 10-time winner on the Korea LPGA Tour, is a rookie on the US circuit. She earned her LPGA membership via an unusual route. Park only got into a handful of tournaments last year as a nonmember but still made enough money in limited opportunities to qualify for full-time status for 2017.

Park started her season with Colin Cann on the bag, but after seven tournaments, she replaced him with a temporary looper, Chris McCalmont, before hiring Jones as her new full-time caddie in May.

Jones has previously worked with two South Korean players: Choi Na-yeon from 2013 to 2015 and Chun In-gee in 2016. Jones was Chun's caddie when she won last year's Evian Championship at 21-under, the lowest score in relation to par at a women's major tournament in history.

At her post-championship press conference, Park said Jones knew exactly what to do with the player in crucial moments.

"Maintaining your focus for 18 holes is the most difficult thing," she said. "One lapse can be costly, and my caddie played a huge role today. He told me jokes to keep me relaxed, and mixed them in with some pep talk when I needed to bear down. That helped me a great deal."

Park was so focused that she wasn't even aware of the presence of US President Donald Trump, the owner of the golf course who attended the final two rounds.

"I saw him yesterday, and though I expected him to attend the final round also, I didn't actually see him," Park said.

With Trump looking on from his seat beside the 15th green, Park made a long birdie putt to claim the outright lead at 10-under. Not knowing the US president was there, Park said, "I was only thinking about making a birdie there because it was a par-five hole."

In addition to the trust she had in Jones, Park, who doesn't have a swing coach and records her own swings for self-analysis, said she also had plenty of faith in herself, even when she was seven shots off the lead through 36 holes at one-under.

"Things weren't going my way in the first and second rounds, but I believed my game would come around in the third and fourth rounds," Park said. "I felt great about my ball striking coming into this championship. I thought I could go low for at least a couple of rounds here, and I am glad I was able to put it together in the third and fourth rounds."

Park also had a chance to win last year's US Women's Open. But she blew her 36-hole lead with a 74-74 finish. She was one off the lead going to the 72nd hole, where she made a bogey and ended two shots out of the playoff.

This year, Park was seven shots out of first place after two rounds, but went 67-67 on the weekend for the victory.

"I think I am more relaxed out on the course compared to last year, and the kind of experience I had at last year's tournament allowed me to win the title today," she said. "My goal was to post a better result than last year, and I am really pleased that I won." (Yonhap)