Rose Zhang defeated Jennifer Kupcho on the second hole of a playoff to punctuate a historic week, winning in her LPGA debut at the inaugural Mizuho Americas Open on Sunday in Jersey City, N.J.

Zhang and Kupcho were tied atop the leaderboard at 9-under 279 and twice replayed the par-4 18th hole atLiberty National Golf Course. Zhang's par the second time through was enough to best Kupcho.

With the win, Zhang will receive full membership on the LPGA Tour, capping her meteoric rise from the amateur ranks to the professional circuit.

The 20-year-old from Stanford won the Augusta National Women's Amateur in April and her second straight NCAA individual title in May. She held the No. 1 spot in the World Amateur Golf Ranking for a record 141 weeks.

Zhang turned pro on May 26, received a sponsor's invite into the Mizuho Americas Open and became the first player since 1951 to win in her LPGA debut.

"What is happening? I just can't believe it," Zhang said on the Golf Channel broadcast. "... To turn pro and come out here (and win) it's just been amazing. I've enjoyed the journey."

Zhang entered Sunday with a two-shot lead and shot a 2-over 74 with two bogeys and no birdies on a day where there were few low scores anywhere at Liberty National, which was hosting an LPGA event for the first time.

Kupcho got in the clubhouse at 9 under with a round of 69, but Zhang, after a bogey at No. 4, held onto the lead at 10 under with 13 consecutive pars. At the par-4 17th, she blew her uphill birdie putt 10 feet past the hole before calmly making the comebacker.

But at the par-4 18th, her drive trickled off the fairway into a bunker. She punched it out toward the green and set up a par look, but the putt leaked right of the cup at the last second.

Both players missed the fairway and scrambled for par on the first playoff hole. Zhang's approach on the second playoff hole landed in a makeable birdie range.

Faced with a long uphill putt, Kupcho thumped her birdie try past the hole and off the green. She missed the comebacker for par, and Zhang two-putted for the victory.

"This golf course is rough," Zhang said. "I really got a bit of everything, got a taste of the pressure, got a taste of the wind and I tried to stay composed as always. I knew that golf was just a grind and you really had to dig deep.

"Once again, that's what I did. I'm glad I'm here."

Kupcho dunked a hole-out eagle at the par-4 seventh to go with three birdies and two bogeys during her round. At the end of the playoff, she congratulated Zhang after playfully squirting her water bottle at her.

Hae Ran Ryu of South Korea shot a 70 to place third at 8 under. Ayaka Furue of Japan (69 on Sunday), Eun-Hee Ji of South Korea (71) and Aditi Ashok of India (74) tied for fourth at 7 under.

Ashleigh Buhai of South Africa fired an 8-under 64 for the round of the day by a wide margin. That got her to 6 under and into a tie for seventh with Ireland's Leona Maguire (67) and Japan's Yuka Saso (70).